1. the last line of a play, story, speech, etc., used to clarify or dramatize a point.
2. a phrase or catchword that becomes identified or associated with a person, group, product, etc., through repetition: Entertainers often develop tag lines, like Ted Lewis's “Is everybody happy?”
3. Mach.(on a crane) a cable for steadying a suspended bucket at the rear. Also,tag'line".
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.