|unison (ˈjuːnɪsən, -zən)|
|a. the interval between two sounds of identical pitch|
|b. (modifier) played or sung at the same pitch: unison singing|
|2.||complete agreement; harmony (esp in the phrase in unison)|
|[C16: from Late Latin ūnisonus, from |
In complete agreement, harmonizing exactly. For example, Their opinion was in unison with ours. [Early 1800s]
Saying the same thing at the same time, simultaneously, as in The whole class answered in unison. [Late 1800s] Both usages allude to the unison of music, a single identical pitch.