means a peculiar, often endearing little behavior, habit, or feature that sets a person or thing apart from the ordinary.

from A 16th-century word that surfaced first meaning a clever verbal twist or quibble, then a sudden flourish or curve — the kind of unexpected swerve a pen makes. Its earlier source is genuinely murky; etymologists shrug rather than fabricate, though it may be related to dialect words for a sharp turn or twist. From a physical kink, it bent toward the figurative: any odd little turn of character that doesn't run straight.