1. Something that gives a minutely faithful representation, image, or idea of something else: Gershwin's music was a mirror of its time.
2. A pattern for imitation; exemplar: a man who was the mirror of fashion. Something worthy of imitation.
3. /Verb/ To reflect as a mirror does
4. /Adjective/ Music. (of a canon or fugue) capable of being played in retrograde or in inversion, as though read in a mirror placed beside or below the music.