theme song: Meaning and Definition of

theme' song"

Pronunciation: [key]
  1. a melody in an operetta or musical comedy so emphasized by repetition as to dominate the presentation.
  2. a melody identifying or identified with a radio or television program, dance band, etc., usually played at the beginning of each program.
  3. an expression, comment, or subject of conversation that a person or group uses habitually.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.