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

In an expansive interview alongside playwright and filmmaker David Mamet, LaBeouf spoke about how his and Coppola's disparate idiosyncrasies often led to frustrations on set of the sprawling sci-fi drama, which had been a decades-long passion project for Coppola but ended up as a high-profile flop. —Jessica Wang, EW.com, 8 May 2025

Those idiosyncrasies are what make the sport so exceptional. —Jim Root, The Athletic, 7 Feb. 2025

Jerry and Emily trotted out more mathematical idiosyncrasies. —Hazlitt, 9 Dec. 2024

Possibly connected to the case which scared James into hiding, Russell (Dipo Ola) serves as the audience’s stand-in, responding to all of his new partner’s idiosyncrasies with a mixture of bewilderment and awe. —Jon O'Brien, IndieWire, 20 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