u•ni•sonˈyu nə sən, -zən(n.)

1. coincidence in pitch of two or more musical tones, voices, etc.

   Category: Music and Dance

2. the performance of musical parts at the same pitch or at the octave.

   Category: Music and Dance

3. a sounding together in octaves, esp. of male and female voices or of higher and lower instruments of the same class.

   Category: Music and Dance

4. a state or process in which all members or elements behave in the same way at the same time.

Idioms for unison:

1. in unison, in perfect accord; in synchrony or agreement: at the same time; all at once:

   to march in unison; My feelings are in unison with yours.

   students shouting answers in unison.

   Category: Idiom

Origin of unison:

1565–75; < ML ūnisonus of a single sound = L ūni-uni - +sonus sound

u•nis′o•nal(adj.)