Unison

noun

1. (acoustics) Identical pitch between two notes or sounds; the simultaneous playing of notes of identical pitch (or separated by one or more octaves).

   "The unison has a pitch ratio of 1:1."

2. (acoustics) A sound or note having the same pitch as another, especially when used as the base note for an interval; a unison string.
3. The state of being in harmony or agreement; harmonious agreement or togetherness, synchronisation.

   "Everyone moved in unison, but the sudden change in weight distribution capsized the boat."