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

• trick
• trait
• characteristic
• quirk
• mannerism
• peculiarity
• eccentricity
• habit
• individualism
• oddity
• singularity
• curiosity
• tic

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

Told over the course of three celebratory gatherings, the film casts a wry look at Dominican identity, middle-class idiosyncrasies and the fragile threads that bind a family together. —Anna Marie De La Fuente, Variety, 5 Sep. 2025

The Brutalist, for all its idiosyncrasies, was a fairly conventional Oscar player—a classically structured paean to a great man. —Radhika Seth, Vogue, 1 Sep. 2025

Admittedly, Honolulu airport has its idiosyncrasies. —Cemile Kavountzis, Travel + Leisure, 24 Aug. 2025

To me, all cats seem autistic, with their unusual idiosyncrasies, blank faces, and sensory sensitivity, but Nini takes it further. —Tao Lin, Harpers Magazine, 20 Aug. 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