unison

1. (music, acoustics) Identical pitch between two notes or sounds; the simultaneous playing of notes of identical pitch (or separated by one or more octaves).Examples: "The unison has a pitch ratio of 1:1."; "The young principal timpanist, Timothy Genis, was superb throughout, though his sidekick timpanist sometimes lagged in the final unisons."uncountableusually

2. (music, acoustics) A sound or note having the same pitch as another, especially when used as the base note for an interval; a unison string.Examples: "I could not behold him without emotion; when he accosted me, his well-known voice made my heart vibrate, like a musical chord, when its unison is struck."uncountableusually

3. (by extension) Two or more voices speaking or singing the same words together.broadlyuncountableusually