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

Victor then flips back to an earlier chapter, before their graduation, to a time when Agnes seems less calcified in her idiosyncrasies. —Katie Walsh, Los Angeles Times, 27 June 2025

Wimbledon is widely considered one of the most prestigious of all tennis Grand Slams, known for its storied grounds, rich traditions, and unique idiosyncrasies. —Jazz Tangcay, Variety, 24 June 2025

And Petrova and Trim, like many others, began to learn the sometimes cruel idiosyncrasies of the U.S. immigration system. —Lauren Villagran, USA Today, 12 May 2025

But at home, my mom, creative and quirky in her own right, embraced my idiosyncrasies. —Ava Xiao-Lin Rigelhaupt, HollywoodReporter, 30 Apr. 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