A peculiarity of behavior; an idiosyncrasy: "Every man had his own quirks and twists" (Harriet Beecher Stowe).
An unpredictable or unaccountable act or event; a vagary: a quirk of fate.
A sudden sharp turn or twist.
An equivocation; a quibble.
Architecture A lengthwise groove on a molding between the convex upper part and the soffit.