1756, from idiosyncrasy + -ic. Earlier in same sense was idiosyncratical (1640s). Related: Idiosyncratically.
we all have our own idiosyncratic gestures
Michelangelo's highly idiosyncratic style of painting
idiolect
idiom
idiomatic
idiopathy
idiosyncrasy
idiosyncratic
idiot
idiotic
idioticon
idiotype
idle
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