idiosyncrasy

noun

id·​i·​o·​syn·​cra·​sy ˌi-dē-ə-ˈsiŋ-krə-sē 

plural idiosyncrasies

1

a

: a peculiarity of constitution or temperament : an individualizing characteristic or quality

b

: individual hypersensitiveness (as to a drug or food)

2

: characteristic peculiarity (as of temperament)

broadly : eccentricity

idiosyncratic

ˌi-dē-ō-(ˌ)sin-ˈkra-tik 

adjective

idiosyncratically

ˌi-dē-ō-(ˌ)sin-ˈkra-ti-k(ə-)lē 

adverb

Synonyms

• crotchet
• curiosity
• eccentricity
• erraticism
• individualism
• kink
• mannerism
• oddity
• peculiarity
• quiddity
• quip
• quirk
• singularity
• tic
• trick
• twist

Examples of idiosyncrasy in a Sentence

Her habit of using “like” in every sentence was just one of her idiosyncrasies.

The current system has a few idiosyncrasies.

Recent Examples on the Web

Japan has some idiosyncrasies about its business culture that make faxing essential, such as the use of a personal seal or hanko, which is used in place of a personal signature, as well as the high value assigned to documents. —Tamsin Gable, Forbes.com, 27 Mar. 2025

In other fields, support specialists identify high-maintenance clients (for example, mechanics understand machine idiosyncrasies, and legal analysts learn which regulations require extra scrutiny). —Rajesh Rajagopalan, Forbes.com, 27 Mar. 2025

Call these objects idiosyncrasies, but each is nonpareil, even the one with the broken nose. —Brian T. Allen, National Review, 22 Mar. 2025

Their value lies in their idiosyncrasies—their passionate insistence on talking about chimps and ancient pyramids, say, rather than the budget ceiling—and in their authenticity, which entails an aversion to memorizing talking points. —Andrew Marantz, The New Yorker, 17 Mar. 2025

Word History

Etymology

Greek idiosynkrasia, from idio- + synkerannynai to blend, from syn- + kerannynai to mingle, mix — more at crater

First Known Use

1604, in the meaning defined at sense 1a

Rhymes for idiosyncrasy

• ethylenediamine
• nanotechnology
• phenomenology
• phenylenediamine
• abc
• absentee
• addressee
• adoptee
• agouti
• allottee
• amphorae
• amputee

Kids Definition

idiosyncrasy

noun

id·​io·​syn·​cra·​sy

ˌid-ē-ə-ˈsiŋ-krə-sē

plural idiosyncrasies

: a way of behaving or thinking that is characteristic of a person

idiosyncratic

ˌid-ē-ō-(ˌ)sin-ˈkrat-ik

adjective

idiosyncratically

-ˈkrat-i-k(ə-)lē

adverb

Medical Definition

idiosyncrasy

noun

id·​io·​syn·​cra·​sy ˌid-ē-ə-ˈsiŋ-krə-sē 

plural idiosyncrasies

1

: a peculiarity of physical or mental constitution or temperament

2

: individual hypersensitiveness (as to a drug or food)

anemia accompanying the use of a sulfa drug is usually considered to be due to idiosyncrasy