in unison

u·ni·son  (yn-sn, -zn)

n.

1. Music

a. Identity of pitch; the interval of a perfect prime.

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

2. The act or an instance of speaking the same words simultaneously by two or more speakers.

3. An instance of agreement; concord.

Idiom:

in unison

1. In complete agreement; harmonizing exactly.

2. At the same time; at once.

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[Middle English, from Old French, from Medieval Latin nisonus, in unison, from Late Latin, monotonous : Latin ni-, uni- + Latin sonus, sound; see swen- in Indo-European roots.]

Thesaurus

Adv.	1.	in unison - speaking or singing at the same time; simultaneously; "they shouted `Yes!' in unison"; "they responded in chorus to the teacher's questions" in chorus
	2.	in unison - at the same pitch; "they sang in unison"