unison

Identity of pitch; the interval of a perfect prime.

The combination of parts at the same pitch or in octaves.

The action of speaking the same words simultaneously.

Performance of an action at the same time.

Agreement; concord.

Sounding alone; unisonous.

In music, sounded simultaneously; specifically, noting two or more voice-parts that are coincident in pitch, or a passage or effect thus produced.

In music: The interval, melodic or harmonic, between any tone and a tone of exactly the same pitch; a perfect prime, acoustically represented by the ratio 1:1. The term is also used as a synonym of prime (as, an augmented unison), though this is objectionable.

The interval of the octave, especially when occurring between male and female voices, or between higher and lower instruments of the same class.