Pronunciation: /əbˈzɔːb/ · Part of speech: verb · Related noun: absorption · Field: general medicine / physiology

Definition. To absorb is to take up or soak up something — especially a liquid — into a solid, or more generally to take a substance into a body, tissue, or material. As in the example, “cotton wads are used to absorb the discharge from the wound,” the term often describes the soaking up of fluids, but in medicine it also has an important physiological meaning.

Two main senses in medicine.

• Physical soaking up. In its simplest sense, “absorb” describes a material drawing in a liquid, as a sponge, dressing, or cotton wad takes up fluid. This is why absorbent materials are widely used in wound care and hygiene.
• Physiological uptake. More importantly in medicine, “absorb” refers to the process by which the body takes substances into its tissues and bloodstream. For example, the small intestine absorbs nutrients from digested food, the bloodstream absorbs oxygen in the lungs, and tissues absorb medication so it can act. This biological process is central to nutrition and to how drugs work.

Absorption in the body. When something is absorbed physiologically, it passes from one compartment (such as the gut, lungs, or skin) into the blood or tissues. The efficiency of absorption affects how much of a nutrient or drug actually becomes available to the body — a concept closely related to bioavailability. Many factors influence it, including the surface area available (the small intestine has a vast surface for this purpose), the properties of the substance, and the health of the absorbing tissue.

Clinical relevance. Absorption matters in several ways. Poor absorption of nutrients (malabsorption) can lead to deficiencies and is seen in various digestive disorders. The route by which a drug is given (by mouth, by injection, through the skin) is chosen partly according to how well and how quickly it will be absorbed. And in wound care, the use of absorbent dressings to take up discharge helps keep wounds clean and supports healing.

Distinction from related terms. Adsorb (note the spelling) is a different process, in which a substance adheres to the surface of a material rather than being taken up into it. Assimilate goes a step further than absorb, meaning to incorporate absorbed substances into the body’s own tissues. Secrete and excrete describe the opposite direction — releasing substances out of cells or the body. “Absorb” specifically denotes the taking in of a substance.

Etymology. From Latin absorbere, “to swallow up” or “to suck in” (ab- = away, from + sorbere = to suck in, to swallow).

⚠️ Disclaimer: This explanation is provided for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional regarding any clinical questions.

Pronunciation: /ˈæbsəluːt ˈælkəhɒl/ · Part of speech: noun · Also called: anhydrous alcohol, absolute ethanol · Field: chemistry / pharmacology

Definition. Absolute alcohol is alcohol that contains no water — that is, ethanol in an essentially pure, water-free form. The word absolute here means “pure” or “free from other substances,” and the term is used to distinguish it from the more common alcohol solutions that contain a proportion of water.

Purity and why water is hard to remove. Ordinary distillation of alcohol and water cannot, on its own, produce pure ethanol. This is because ethanol and water form what chemists call an azeotrope — a mixture that boils at a constant composition (around 95–96% ethanol and 4–5% water by volume). At that point the two cannot be separated by simple distillation alone. To obtain absolute alcohol, the remaining water must be removed by special methods, such as adding a drying (dehydrating) agent or using other separation techniques. Absolute alcohol is typically defined as containing at least 99% ethanol, with negligible water.

Uses. Because it is essentially water-free and of high purity, absolute alcohol is used where the presence of water would interfere:

• As a solvent in chemical reactions and analyses that must be carried out under water-free conditions.
• In pharmaceutical and laboratory preparations requiring a pure ethanol base.
• In certain industrial processes, and historically in some medical applications.

Important safety note. Absolute alcohol is pure ethanol and is not intended for drinking. Industrial or laboratory ethanol is frequently denatured — additives are included to make it toxic or unpalatable — so that it cannot be consumed; such products can be poisonous. Even pure ethanol is harmful in the quantities and concentrations used in the laboratory. It is also highly flammable and must be handled with appropriate care.

Distinction from related terms. Rectified spirit is the common high-strength alcohol-water mixture (about 95–96% ethanol) obtained by ordinary distillation, which still contains water. Denatured alcohol (methylated spirit) is ethanol made unfit to drink by additives. Surgical spirit and rubbing alcohol are alcohol-based products formulated for external use. Absolute alcohol specifically denotes ethanol from which the water has been removed.

Etymology. Absolute from Latin absolutus, “freed, complete, unrestricted” (here meaning free from water); alcohol via medieval Latin from Arabic al-kuhl, originally referring to a fine powder and later to a purified or distilled essence.

⚠️ Disclaimer: This explanation is provided for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Absolute and denatured alcohols are not for human consumption and can be dangerous. Always consult a qualified healthcare professional regarding any clinical questions.

Pronunciation: /ˈæbsɛs/ · Part of speech: noun · Plural: abscesses · Field: general medicine / surgery

Definition. An abscess is a painful, swollen area where pus forms — a localised collection of pus that builds up within the tissues of the body. It typically develops as the body’s response to infection, as in the examples “She had an abscess under a tooth” or when “the doctor decided to lance the abscess.”

How it forms. An abscess usually arises when bacteria (or sometimes other organisms) invade the tissue and the body mounts a defensive response. White blood cells travel to the site to fight the infection, and the resulting mixture of dead white cells, bacteria, and damaged tissue forms pus. The body walls off this collection within a cavity to contain the infection. As pus accumulates, pressure builds, producing the characteristic pain, swelling, redness, and warmth. As the dictionary note states, the formation of an abscess is often accompanied by a high temperature (fever), reflecting the body’s systemic response to infection.

Common sites. Abscesses can develop almost anywhere in the body. Familiar examples include:

• Skin abscesses (boils), in the skin and underlying tissue.
• Dental abscesses, around the root of a tooth or in the gum.
• Internal abscesses, in organs such as the liver, lung, or brain, or within body cavities, which are more serious and harder to detect.

Acute versus chronic. As the comment explains, the type of abscess guides treatment:

• An acute abscess develops quickly and, once enough pus has formed, is generally dealt with by incision and drainage — opening it to let the pus out (sometimes described as lancing the abscess).
• A chronic abscess develops more slowly and is usually treated with drugs, such as antibiotics, although drainage may still be needed.

Clinical relevance. Draining the pus is often the key step in treating an abscess, because antibiotics alone may not penetrate well into a walled-off collection. Antibiotics are used in addition when infection is spreading or in certain locations. Internal abscesses may require imaging to locate them and specialised drainage procedures. An untreated abscess can enlarge, spread infection to surrounding tissue or the bloodstream, and become dangerous, so medical assessment is important — and an abscess should not be squeezed or opened without proper care.

Distinction from related terms. A cyst is a closed sac that may contain fluid but is not necessarily infected or full of pus. Cellulitis is a spreading infection of the skin and soft tissue without a walled-off pus collection. A boil (furuncle) is a specific type of skin abscess centred on a hair follicle. An empyema is a collection of pus within an existing body cavity. An abscess is specifically a localised, walled-off collection of pus.

Etymology. From Latin abscessus, “a going away” (ab- = away + cedere = to go) — reflecting the old idea that the diseased matter “departed” from the body and gathered at one site.

⚠️ Disclaimer: This explanation is provided for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Do not attempt to open or drain an abscess yourself. Always consult a qualified healthcare professional regarding any clinical questions.

Pronunciation: /əˌbrʌptiəʊ pləˈsɛntiː/ · Part of speech: noun · Also called: placental abruption · Field: obstetrics

Definition. Abruptio placentae is an occasion when the placenta suddenly comes away from the wall of the uterus earlier than it should — that is, before the baby is born — often causing shock and bleeding. It is also known as placental abruption. It is an obstetric emergency because it can threaten the life of both mother and baby.

What happens. Normally, the placenta stays firmly attached to the inner wall of the uterus throughout pregnancy, supplying the fetus with oxygen and nutrients, and separates only after the baby has been delivered. In abruptio placentae, part or all of the placenta detaches prematurely. Bleeding occurs at the site of separation, which can reduce the supply of oxygen and nutrients to the fetus and cause significant blood loss in the mother.

Concealed versus revealed bleeding. An important feature is that the bleeding is not always visible:

• Revealed — blood escapes through the cervix and appears as vaginal bleeding.
• Concealed — blood is trapped behind the placenta inside the uterus, so there may be little or no visible bleeding even though substantial blood loss is occurring. This can make the condition more dangerous, because the severity may be underestimated.

Typical features. Common signs and symptoms include sudden abdominal pain, a tender and often hard (“woody”) uterus, vaginal bleeding (which may be absent in concealed cases), uterine contractions, and signs of fetal distress. In severe cases the mother may show signs of shock from blood loss.

Risk factors. Recognised factors associated with placental abruption include high blood pressure (including pre-eclampsia), abdominal trauma, a previous abruption, smoking and certain drug use, multiple pregnancy, and advanced maternal age, among others. In many cases, however, no single cause is identified.

Clinical relevance. Abruptio placentae is a medical emergency requiring urgent assessment. Management depends on the severity of the separation, the amount of bleeding, the gestational age, and the condition of mother and baby. It may range from close monitoring to urgent delivery, often by caesarean section, together with treatment of blood loss. Because it can deteriorate rapidly, sudden severe abdominal pain or bleeding in pregnancy always warrants immediate medical attention.

Distinction from related terms. Placenta praevia is a different condition in which the placenta lies low and covers or is near the cervix, also causing bleeding but by a different mechanism and typically painless. Antepartum haemorrhage is the general term for bleeding from the genital tract in later pregnancy, of which abruption is one cause. Abruptio placentae specifically denotes the premature separation of a normally positioned placenta.

Etymology. From Latin abruptio, “a breaking off” (ab- = away + rumpere = to break), and placentae, “of the placenta” (Latin placenta, “flat cake,” describing its shape) — literally, “a breaking away of the placenta.”

⚠️ Disclaimer: This explanation is provided for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Sudden severe pain or bleeding in pregnancy is a medical emergency — seek immediate care. Always consult a qualified healthcare professional regarding any clinical questions.

Pronunciation: /ˌæbriˈækʃən/ · Part of speech: noun · Verb form: to abreact · Field: psychology / psychoanalysis

Definition. Abreaction is the treatment of a person with a neurosis by encouraging him or her to think again about past distressing experiences. More broadly, it refers to the release of emotional tension that comes from re-living or re-expressing the feelings attached to a buried or traumatic memory. It is the noun form of the verb abreact.

The underlying concept. Abreaction is one of the foundational ideas of early psychoanalysis, developed in the work of Josef Breuer and Sigmund Freud. The theory holds that emotions connected to a distressing or repressed experience can remain “trapped” in the unconscious mind, where they continue to produce distress or symptoms. By deliberately recalling the experience and giving expression to the emotion that was originally held back, the person discharges this pent-up feeling. The emotional release is the abreaction itself; the relief and resolution that may follow was historically called catharsis.

How it works as a treatment. As the definition indicates, abreaction was used as a therapeutic method: the person is guided to revisit past bad experiences and to express the emotions associated with them, rather than keeping them suppressed. Historically, this was sometimes facilitated through hypnosis or, in some cases, with the aid of certain drugs (so-called “narcoanalysis”). The aim was that, once the buried emotion was released and the experience consciously processed, the related neurotic symptoms would ease.

Clinical relevance and cautions. The concept was influential in the development of “talking therapies.” However, modern trauma care recognises that simply re-living a painful experience is not automatically helpful and can be harmful if done without skill and support, because it may re-traumatise the person. Contemporary evidence-based trauma treatments are carefully structured to process difficult memories safely. Abreaction is therefore best understood both as a historically important psychoanalytic idea and as a process that should only be undertaken with a trained mental health professional.

Distinction from related terms. Catharsis is the emotional relief or “purging” that may follow abreaction. Repression is the unconscious mechanism that keeps distressing material out of awareness, which abreaction aims to undo. Neurosis is the older term for the kind of psychological distress the treatment was meant to address. Desensitisation is a more structured modern process of reducing emotional reactivity to a memory. Abreaction specifically names the therapeutic release of emotion through re-experiencing past events.

Etymology. A translation of the German Abreagieren, from ab- (“away, off”) + reagieren (“to react”) — literally, the “reacting away” or discharge of the emotion attached to a memory.

⚠️ Disclaimer: This explanation is provided for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare or mental health professional regarding any clinical or personal questions.

Pronunciation: /ˌæbriˈækt/ · Part of speech: verb · Related noun: abreaction · Field: psychology / psychoanalysis

Definition. To abreact is to release unconscious psychological tension by talking about, or repeatedly remembering, the events that caused it. The idea is that buried emotional energy attached to a distressing memory can be discharged when the person brings that memory back to awareness and re-experiences the associated feelings.

The underlying concept. Abreaction is a term rooted in early psychoanalytic theory, particularly the work of Sigmund Freud and Josef Breuer. The central notion is that emotions linked to a traumatic or repressed experience may remain “bottled up” in the unconscious mind, where they continue to cause distress or symptoms. By re-living the experience — recalling it vividly and expressing the emotion that was originally held back — the person is thought to release this pent-up feeling, which may bring a sense of relief. This emotional discharge is the abreaction; the related relief and resolution was historically termed catharsis.

How it is used in therapy. Abreaction may occur spontaneously, or it may be encouraged within certain forms of psychotherapy. The person is helped to recall and talk through a distressing event in a safe, supported setting so that the associated emotions can be expressed rather than suppressed. Historically, various methods (including hypnosis) were used to facilitate it. In modern practice, helping someone process difficult memories is approached carefully, because re-experiencing trauma can itself be distressing and needs to be handled by a trained professional in a supportive environment.

Clinical relevance and cautions. While the concept influenced the development of “talking therapies,” contemporary trauma treatment recognises that simply re-living a traumatic event is not automatically beneficial and can sometimes be harmful if done without proper support and skill. Evidence-based trauma therapies are structured to process difficult memories safely. For this reason, abreaction is best understood both as a historical psychoanalytic idea and as a phenomenon that should be guided by a qualified mental health professional.

Distinction from related terms. Catharsis refers to the emotional relief or purging that may follow abreaction. Repression is the unconscious pushing-away of distressing material that abreaction seeks to release. Desensitisation is a more structured therapeutic process of reducing emotional reactivity to a memory or stimulus. Abreaction specifically denotes the release of tension through re-experiencing the originating event.

Etymology. A translation of the German Abreagieren, formed from ab- (“away, off”) and reagieren (“to react”) — literally, to “react away” or discharge the emotion attached to a memory.

⚠️ Disclaimer: This explanation is provided for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare or mental health professional regarding any clinical or personal questions.

Pronunciation: /əˈbreɪʒ(ə)n/ · Part of speech: noun · Field: general medicine / dermatology · Common term: graze, scrape

Definition. An abrasion is a condition in which the surface of the skin has been rubbed off by a rough surface, leaving a raw area that may bleed. In everyday language it is called a graze or a scrape. It is a superficial wound, affecting mainly the outer layers of the skin rather than penetrating deeply.

How it occurs. Abrasions typically result from friction — when the skin is dragged across a hard or rough surface, such as in a fall onto pavement, gravel, or a sports field (“road rash” is a common example). The mechanical rubbing removes the outermost skin layers (the epidermis and sometimes the upper dermis), exposing the more sensitive tissue beneath. Because many small blood vessels and nerve endings lie close to the surface, abrasions often sting, ooze, or bleed slightly even though they are not deep.

Why even minor abrasions matter. As the accompanying comment stresses, intact skin is an efficient barrier against bacteria, so any break in it — even a minor one — can let infection enter the body. For this reason, abrasions should be cleaned and treated with an antiseptic. General first-aid principles for a minor abrasion are to gently clean the area to remove dirt and debris, apply an antiseptic, and cover it if needed to keep it clean while it heals. Larger, deeper, heavily contaminated, or non-healing wounds, or any showing signs of infection (increasing redness, swelling, warmth, pus, or fever), should be assessed by a healthcare professional.

Healing. Because abrasions are superficial, they usually heal well, often without scarring, as the skin regenerates from the surrounding and underlying cells. Keeping the wound clean supports healing and reduces the risk of infection.

Other meanings. The word abrasion is also used in dentistry, where dental abrasion refers to the wearing away of tooth surface by mechanical forces such as over-vigorous brushing. More generally, “abrasion” can describe any wearing away of a surface by rubbing.

Distinction from related terms. A laceration is a cut or tear that penetrates more deeply, with torn rather than rubbed edges. An incision is a clean cut, such as from a blade. A contusion (bruise) involves damage to tissues beneath intact skin. A puncture is a deep, narrow wound. An abrasion is distinguished by being a superficial scraping away of the skin surface.

Etymology. From Latin abrasio, from abradere, “to scrape off” (ab- = away + radere = to scrape) — literally, a scraping away.

⚠️ Disclaimer: This explanation is provided for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional regarding any clinical questions or before treating a wound.

Pronunciation: /ˌeɪ biː ˈəʊ ˈsɪstəm/ · Part of speech: noun · Field: haematology / transfusion medicine

Definition. The ABO system is a system of classifying blood groups. It sorts human blood into types according to the presence or absence of certain markers (antigens) on the surface of the red blood cells, and it is the most important system used in matching blood for transfusion.

The four blood groups. Under the ABO system, blood is divided into four main groups based on which antigens the red cells carry:

• Group A — red cells carry the A antigen; the plasma contains anti-B antibodies.
• Group B — red cells carry the B antigen; the plasma contains anti-A antibodies.
• Group AB — red cells carry both A and B antigens; the plasma contains neither anti-A nor anti-B antibodies.
• Group O — red cells carry neither A nor B antigen; the plasma contains both anti-A and anti-B antibodies.

Antibodies and compatibility. A key feature of the ABO system is that people naturally have antibodies against the antigens they do not possess. If incompatible blood is given — for example, group A blood to a group B recipient — these antibodies attack the transfused red cells, causing them to clump together (agglutinate) and break down. This reaction can be severe or fatal, which is why ABO matching is essential before transfusion.

Universal donor and recipient. Because of this antibody pattern:

• Group O (specifically O negative) is often called the universal donor, since its red cells carry neither A nor B antigen and are less likely to provoke a reaction.
• Group AB is often called the universal recipient, since its plasma lacks both anti-A and anti-B antibodies and can therefore receive red cells of any ABO type. (These terms apply chiefly to red cell transfusion and are simplifications, since other blood-group systems also matter.)

The Rh (Rhesus) system. The ABO system is almost always considered together with the Rh (Rhesus) factor, another important blood-group system. A person is described as Rh-positive or Rh-negative depending on whether they carry the RhD antigen, giving familiar combined types such as A positive or O negative.

Clinical relevance. ABO grouping is fundamental to safe blood transfusion, organ transplantation, and the management of pregnancy (where blood-group incompatibility between mother and baby can sometimes cause problems). Cross-matching blood before transfusion ensures donor and recipient are compatible.

Etymology. The system is named simply for the antigens it classifies — A, B, and O — where “O” originally denoted the absence of A and B antigens. It was discovered by Karl Landsteiner in the early twentieth century, work for which he received the Nobel Prize.

⚠️ Disclaimer: This explanation is provided for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional regarding any clinical questions.

Pronunciation: /əˈbɔːtəs ˈfiːvə/ · Part of speech: noun · Field: infectious disease · Synonym: brucellosis

Definition. Abortus fever is another name for brucellosis, an infectious disease caused by bacteria of the genus Brucella. The name comes from the species Brucella abortus, one of the main bacteria responsible, which is well known for causing contagious abortion (loss of pregnancy) in cattle.

Other names. Brucellosis is known by several names, reflecting its history and the way it spreads: abortus fever, undulant fever (because the fever tends to rise and fall in a wave-like pattern), Malta fever and Mediterranean fever (after regions where it was historically common), and Bang’s disease (after the scientist who identified Brucella abortus).

Cause and transmission. The disease is a zoonosis — an infection that passes from animals to humans. People usually become infected through:

• Consuming unpasteurised dairy products such as raw milk or soft cheeses from infected animals.
• Direct contact with the tissues, blood, or birth fluids of infected animals, which puts farmers, veterinarians, slaughterhouse workers, and laboratory staff at particular risk.
• Inhaling contaminated airborne particles in certain settings.

It is only rarely spread directly from person to person.

Typical features. Brucellosis often causes non-specific, flu-like symptoms that can make it difficult to recognise. These commonly include a fluctuating (“undulant”) fever, sweats, fatigue, malaise, loss of appetite, headache, and muscle and joint pain. The illness can become chronic and may affect various organs, sometimes involving the joints, liver, spleen, heart, or nervous system if not treated.

Clinical relevance. Because its symptoms overlap with many other illnesses, brucellosis is diagnosed with the help of blood tests and cultures and a history of possible exposure (such as occupational contact with animals or consumption of unpasteurised products). It is generally treated with a prolonged course of antibiotics, often using more than one drug to reduce the chance of relapse. Public-health control focuses on animal vaccination, testing and management of livestock, and pasteurisation of milk.

Distinction from related terms. Brucellosis is the standard medical name for the human disease. Contagious abortion or Bang’s disease refers chiefly to the disease in cattle. Undulant fever emphasises the characteristic fever pattern. “Abortus fever” highlights the link to Brucella abortus; all refer to essentially the same infection.

Etymology. Abortus from Latin aboriri, “to miscarry” (reflecting the bacterium’s effect of causing abortion in animals); fever from Latin febris. The genus name Brucella honours David Bruce, who first identified the organism.

⚠️ Disclaimer: This explanation is provided for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional regarding any clinical questions.

Pronunciation: /əˈbɔːtəs/ · Part of speech: noun · Field: obstetrics / pathology

Definition. An abortus is a fetus that is expelled from the uterus during an abortion or miscarriage. The term refers to the products of a pregnancy that ends before the fetus is fully developed — that is, to the expelled fetus itself.

How the term is used. Abortus is a clinical and technical term, used mainly in medical, pathological, and laboratory contexts rather than in everyday speech. It may be used when the expelled tissue is examined to help understand why a pregnancy ended — for example, to investigate the cause of a miscarriage or a recurrent pregnancy loss. In some classifications the word is also used loosely to refer to the event or to a fetus expelled below a defined weight or gestational threshold.

Related contexts. The word appears in a few specific settings:

• Pathological examination — the abortus may be sent for study to look for chromosomal abnormalities, infection, or structural problems that could explain the loss.
• Microbiology — the species name Brucella abortus uses the same Latin root, because this bacterium causes contagious abortion (loss of pregnancy) in cattle and is one cause of brucellosis in humans. This is a separate usage but shares the underlying meaning of “miscarriage.”

Clinical relevance. Examining an abortus can provide valuable information after a pregnancy loss. Identifying a chromosomal or structural cause may help explain why the loss occurred, guide counselling, and inform the management of future pregnancies. Such investigation is carried out sensitively and with appropriate consent, recognising that pregnancy loss is often a distressing experience.

Distinction from related terms. Abortion names the event or procedure; to abort is the verb; an abortifacient is an agent that provokes an abortion. Products of conception is a broader clinical term covering all the tissue from a pregnancy (including the placenta and membranes), whereas abortus refers specifically to the expelled fetus.

Etymology. From Latin abortus, the past participle of aboriri, “to miscarry” or “to fail to be born” (ab- = away, amiss + oriri = to arise, to be born) — literally, “that which has miscarried.”

⚠️ Disclaimer: This explanation is provided for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional regarding any clinical questions.