noun sounding alone.
2. unison ·noun a single, unvaried.
3. unison ·noun harmony; agreement; concord; union.
4. unison ·noun sounded alike in pitch; unisonant; unisonous; as, unison passages, in which two or more parts unite in coincident sound.
5. unison ·noun 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.