Meaning of heads up

heads' up'

Pronunciation: [key]
  1. (used interjectionally to call attention to an impending danger or the need for immediate alertness).


Pronunciation: (hedz'up"), [key]
— adj.
  1. quick to grasp a situation and take advantage of opportunities; alert; resourceful.
  1. a warning: sending a heads-up to the Pentagon about possible attacks.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.