(1) To abort a carrier based landing by visually signaling to a pilot
(2) To signal or indicate to a pilot that an approach should be aborted
(3) To signal to anyone that proceeding is not going to work or is not advisable
(1) "Wave him off until we clear the wreckage off the deck"
(2) "I was trying to land during an earthquake so they had to wave me off"
(3) "I was hitting on a married chick until my wing man waved me off."