idiosyncrasy

First attested in 1604, in modern sense since 1665, from Ancient Greek ἰδιοσυγκρασία (idiosunkrasía, “one’s own temperament”), from ἴδιος (ídios, “one’s own”) + σύν (sún, “together”) + κρᾶσις (krâsis, “temperament”). By surface analysis, idio- +‎ syn- +‎ -crasy.

• (Received Pronunciation) IPA^(key): /ˌɪdɪəʊˈsɪŋkɹəsi/, /ˌɪdɪəˈsɪŋkɹəsi/
• (General American) IPA^(key): /ˌɪdiəˈsɪŋkɹəsi/, /ˌɪdioʊˈsɪŋkɹəsi/
• (General Australian) IPA^(key): /ˌɪdiəˈsɪŋkɹəsi/

  • Audio (Queensland):

    (file)

• (New Zealand) IPA^(key): /ˌədiəˈsəŋkɹəsi/
• Hyphenation: idio‧syn‧crasy

idiosyncrasy (plural idiosyncrasies)

1. A behavior or way of thinking that is characteristic of a person or a group.

   Synonyms: eccentricity, foible, habit, idiocrasy, mannerism, oddity, quirk, vagary

   • 1851 April 9, Nathaniel Hawthorne, The House of the Seven Gables, a Romance, Boston, Mass.: Ticknor, Reed, and Fields, →OCLC:

     This mode of death had been an idiosyncrasy with his family, for generations past; not often occurring, indeed, but, when it does occur, usually attacking individuals about the Judge’s time of life, and generally in the tension of some mental crisis, or, perhaps, in an access of wrath.

   • 1891, Thomas Hardy, Tess of the d’Urbervilles: A Pure Woman Faithfully Presented […], volume (please specify |volume=I to III), London: James R[ipley] Osgood, McIlvaine and Co., […], →OCLC:

     Every village has its idiosyncrasy, its constitution, often its own code of morality.

   • 1898 [1884], Philip Gilbert Hamerton, “Independence”, in Human Intercourse‎^[1]:

     If he expresses himself such as he is, an idiosyncrasy affected but not annihilated by education, he may say that his books are his own.

   • 1980, Paul Schrader, American Gigolo, spoken by Anne (Nina van Pallandt):

     She's flying in from Stockholm on Thursday. She apparently has certain sexual idiosyncrasies.

   • 2026 January 1, Carlos Lozada, “How Did We Get to Such a Bad Question?”, in The New York Times‎^[2], New York, N.Y.: The New York Times Company, →ISSN, →OCLC:

     The trouble with this question is that it removes the focus from the substance of whatever event or debate is being discussed, redirecting it to the speaker’s or writer’s personal perceptions or expectations about it — away from facts and toward idiosyncrasy.

     (Can we archive this URL?)

2. (medicine, originally) A peculiar individual reaction to a generally innocuous substance or factor; a risk factor.

   Coordinate term: diathesis

   • 1642, [Thomas Browne], “The Second Part”, in Religio Medici, London: […] Andrew Crooke, →OCLC, page 111:

     […] I have no antipathy, or rather Idio-ſyncraſie, in dyet, humour, ayre, any thing; […] .

   • 1927, Humphry Davy Rolleston, Idiosyncrasies, London: Kegan Paul, pages 16–17:

     There are, however, distinct differences between diatheses and idiosyncrasies; diatheses definitely tend to the development of disease, for example the scrofulous diathesis of our forebears favours the onset of tuberculosis; idiosyncrasies are abnormal reactions but do not necessarily dispose to disease.

3. A peculiarity that serves to distinguish or identify.

   He mastered the idiosyncrasies of English spelling and speech.

• idiosyncratic
• idiosyncratically

• William Dwight Whitney, Benjamin E[li] Smith, editors (1911), “idiosyncrasy”, in The Century Dictionary […], New York, N.Y.: The Century Co., →OCLC.
• “idiosyncrasy”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.