What does the word quirk mean?

Usage examples for quirk

  1. " This was a real horse on a real flight to the winning- post," added Crozier, with a quirk at the corner of his mouth. – You Never Know Your Luck, Complete Being The Story Of A Matrimonial Deserter by Gilbert Parker Last Updated: March 14, 2009
  2. He couldn't answer that one either, unless if it were as Charles suggested: Sophia had studied Lucy so carefully, had learned her likes and dislikes, her wants and desires, had memorized and practised every quirk of her character to such an extent that Sophia was Lucy in essence. – Voyage To Eternity by Milton Lesser