Music and Acoustics. Identical in pitch (to something) or one or more octaves apart; singing, sounding, etc., in unison.

Music. Of the same pitch; composed or performed in unison or in octaves, and not in parts.

Of the same pitch; = unisonous, adj. 1.

Music. = homophonic, adj. 1.

Of the same pitch or sound; unisonous. In later use frequently in figurative context.

Producing, or consisting of, sounds of the same pitch; unisonous, in unison. Said of ancient music; opposed to antiphonic.