idiosyncrasy

id·io·syn·cra·sy

noun \ˌid-ē-ə-ˈsiŋ-krə-sē\

plural id·io·syn·cra·sies

Definition of IDIOSYNCRASY

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>