a group that works together as a whole or produces a single effect, e.g.:
a complete outfit of matching garments
(treated as sing. or pl) a combination of two or more performers or players, esp a musical group having only one instrument playing each part
(treated as sing. or pl) a group of actors, supporting players, singers, or dancers who perform together on a roughly equal footing
a section involving all the performers
the quality of togetherness in performance
The quartet's ensemble was poor
[French ensemble together, from Latin insimul at the same time, from in-2 + simul at the same time]