Idiosyncrasy

An idiosyncrasy is an unusual feature of a person (though there are also other uses, see below). It also means odd habit. The term is often used to express eccentricity or peculiarity. A synonym may be "".

The term "idiosyncrasy" originates from Greek idiosynkrasía, "a peculiar temperament, habit of body" (from idios, "one's own", syn, "with" and krasis, "mixture").

The term can also be applied to symbols or words. Idiosyncratic symbols mean one thing for a particular person, as a blade could mean war, but to someone else, it could symbolize a surgery. By the same principle, linguists (such as Ferdinand de Saussure) state that words are not only arbitrary, but also largely idiosyncratic signs.

Idiosyncrasy defined the way physicians conceived diseases in the 19th century. They considered each disease as a unique condition, related to each patient. This understanding began to change in the 1870s, when discoveries made by researchers in Europe permitted the advent of a "scientific medicine", a precursor to the evidence-based medicine that is the standard of practice today.

The term idiosyncratic drug reaction denotes an aberrant or bizarre reaction or hypersensitivity to a substance, without connection to the pharmacology of the drug. It is what is known as a Type B reaction. Type B reactions have the following characteristics: They are usually unpredictable, might not be picked up by toxicological screening, not necessarily dose-related, incidence and morbidity low but mortality is high. Type B reactions are most commonly immunological (e.g. penicillin allergy)

In psychiatry, the term means a specific and unique mental condition of a patient, often accompanied by neologisms. In psychoanalysis and behaviorism, it is used for the personal way a given individual reacts, perceives and experiences a common situation: a certain dish made of meat may cause nostalgic memories in one person and disgust in another. These reactions are called idiosyncratic.

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