1. A peculiarity of behavior; an idiosyncrasy: "Every man had his own quirks and twists" (Harriet Beecher Stowe).
2. An unpredictable or unaccountable act or event; a vagary: a quirk of fate.
3. A sudden sharp turn or twist: a quirk of the head.
4. Architecture A lengthwise groove on a molding between the convex upper part and the soffit.
5. Archaic An equivocation; a quibble.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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