1. Cricket.the knocking off by one bowler of three wickets with three successive pitches: so called because formerly such a bowler was rewarded with a hat.
2. Ice Hockey, Soccer.three goals or points scored by one player in one game.
3. Baseball.a series of a base hit, a two-base hit, a three-base hit, and a home run achieved in any order by one player in one game.
4. a clever or adroitly deceptive maneuver.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.