[yoo-nuh-suh
n, -zuhn] 
| 1. | coincidence in pitch of two or more musical tones, voices, etc. |
| 2. | the musical interval of a perfect prime. |
| 3. | the performance of musical parts at the same pitch or at the octave. |
| 4. | a sounding together in octaves, esp. of male and female voices or of higher and lower instruments of the same class. |
| 5. | a process in which all elements behave in the same way at the same time; simultaneous or synchronous parallel action: to march in unison. |
| 6. | in unison, in perfect accord; corresponding exactly: My feelings on the subject are in unison with yours. |
| u·ni·son (yōō'nĭ-sən, -zən) n.
[Middle English, from Old French, from Medieval Latin ūnisonus, in unison, from Late Latin, monotonous : Latin ūni-, uni- + Latin sonus, sound; see swen- in Indo-European roots.] |