n. - Harmony; agreement; concord; union.
n. - 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.
n. - A single, unvaried.
n. - Sounding alone.
n. - Sounded alike in pitch; unisonant; unisonous; as, unison passages, in which two or more parts unite in coincident sound.