idiosyncrasy
- A distinctive personal quirk, habit, or characteristic that sets an individual apart from others.
- In medicine, an unusual individual reaction to a drug or substance, differing from the normal response.
In a sentence
- One of the professor's most endearing idiosyncrasies was his habit of humming softly while grading papers.
- The software's idiosyncrasies took new users weeks to learn, but veteran employees navigated them effortlessly.
Usage note. Spelling is notoriously difficult: the word has five syllables, an easy-to-forget 'y' before the '-crasy' ending, and the '-sync-' cluster in the middle. Break it apart as 'idio + sync + rasy' to remember it.
Where it comes from
English idiosyncrasy — “personal quirk or trait” · entered English early 17th c.
From Greek 'idiosugkrasia', built from 'idios' (one's own, personal), 'sun' (together), and 'krasis' (mixture, blending), literally meaning 'a personal mixture of humors' under ancient medical theory. The term entered English via Late Latin in the early 17th century. Its original sense was medical, referring to a person's unique bodily constitution, before broadening to mean any personal peculiarity (source: Oxford, Etymonline).