/ Dictionary / Index K key signature: Meaning and Definition of Find definitions for: key' sig"nature Pronunciation: [key] — Music. Music. (in notation) the group of sharps or flats placed after the clef to indicate the tonality of the music following. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Keyserling keyslot Related Content Daily Word Quiz: cetacean Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language