harmonious agreement or union
identity in musical pitch
the writing, playing, or singing of parts in a musical passage at the same pitch or one or more octaves apart
(used before a noun) played or sung in unison
in unison
in perfect agreement or harmony
saying or doing the same thing at the same time
But when all the arts journalists in London start fluffing up their tail feathers in unison, the effect is not so much of natural compulsion as of chummy conspiracy — Independent
unisonous adj
[Middle English via French from late Latin unisonus having the same sound, from Latin uni- + sonus sound]