Unison

Part of speech: noun (n.)

1. Harmony; agreement; concord; union.

2. 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.

3. A single, unvaried. [R.] Pope. In unison, in agreement; agreeing in tone; in concord.

Part of speech: adjective (a.)

1. Sounding alone. [Obs.] [sounds] intermixed with voice, Choral or unison. Milton.

2. Sounded alike in pitch; unisonant; unisonous; as, unison passages, in which two or more parts unite in coincident sound.