Cooperator

·noun One who labors jointly with others to promote the same end.

cooperator
cŏ-ŏpĕrātor, ōris, m., a joint-laborer, co-operator (eccl. Lat.), Hier. Ep. 143, 1; Aug. Civ. Dei...

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.