Merriam-Webster's Collegiate® Dictionary, 11th Edition
PARTISAN
I. noun also partizan
Etymology: Middle French partisan, from north Italian dialect partiźan, from part part, party, from Latin part-, pars part
Date: 1555
a firm adherent to a party, faction, cause, or person,
2. a member of a body of detached light troops making forays and harassing an enemy, a member of a guerrilla band operating within enemy lines, see: follower partisan adjective partisanly adverb partisanship noun
II. noun or partizan
Etymology: Middle French partisane, from north Italian dialect partiźana, feminine of partiźan
Date: 1556
a weapon of the 16th and 17th centuries with long shaft and broad blade