Main Entry: uni·son

Pronunciation: \ˈyü-nə-sən, -nə-zən\

Function: noun

Etymology: Middle English unisoun, from Middle French unisson, from Medieval Latin unisonus having the same sound, from Latin uni- + sonus sound — more at sound

Date: 15th century

1 a : identity in musical pitch; specifically : the interval of a perfect prime b : the state of being so tuned or sounded c : the writing, playing, or singing of parts in a musical passage at the same pitch or in octaves
2 : a harmonious agreement or union : concord

— unison adjective

— in unison 1 : in perfect agreement : so as to harmonize exactly <a class reciting in unison>
2 : at the same time : simultaneously