partisan

noun

• 1a strong supporter of a party, cause, or person: partisans of the exiled Stuarts

• 2a member of an armed group formed to fight secretly against an occupying force, in particular one operating in German-occupied Yugoslavia, Italy, and parts of eastern Europe in the Second World War: the partisans opened fire from the woods [as modifier]:it is not in the nature of partisan warfare to produce victory in the field

adjective

• prejudiced in favour of a particular cause:newspapers have become increasingly partisan