harmony; agreement; concord; union.-identity in pitch; coincidence of sounds proceeding from an equality in the number of vibrations made in a given time by two or more sonorous bodies. parts played or sung in octaves are also said to be in unison, or in octaves.-a single, unvaried.-sounding alone.-sounded alike in pitch; unisonant; unisonous; as, unison passages, in which two or more parts unite in coincident sound.