Idiosyncrasy
[id-ee-uh-sing-kruh-see, -sin-]
–noun, plural -sies.
1. a characteristic, habit, mannerism, or the like, that is peculiar to an individual.
2. the physical constitution peculiar to an individual.
3. a peculiarity of the physical or the mental constitution, esp. susceptibility toward drugs, food, etc. Compare allergy (def. 1).
Also, idiocrasy.
Origin:
1595–1605; < Gk idiosynkrāsía, equiv. to idio- idio- + syn- syn- + krâs(is) a blending + -ia -y 3
Synonyms:
1. peculiarity, quirk.