I. -_nə̇st noun
( -s )
Etymology: collaboration + -ist
: one that advocates or practices collaboration with an enemy (as an invader or part of an occupying force) or with some other group opposed or antagonistic to his own
punishment for collaborationists after the liberation
II. adjective
: of or relating to a collaborationist
the collaborationist tricks by which the success of the occupation was assured — Ann F. Wolfe