Synonyms for Leftist (same or very similar meaning)
WordNet sense 1 (a person who belongs to the political left):
collectivist, left-wingerWordNet sense 2 (believing in or supporting tenets of the political left):
left-wing, left-of-centerWordNet sense 3 (of or belonging to the political or intellectual left):
leftFrom the ODE community, based on WordNetadd/edit