Definition of: partisan

(pär′tə·zən) adjective
1. Relating to or unreasonably devoted to a party or faction.
2. Pertaining to or carried on by partisans or irregular troops.
—noun
1. An adherent and upholder of an individual or of a party or cause; especially, a blind or fanatical adherent or devotee.
2. A member of a body of detached or irregular troops; a guerilla. See synonyms under ADHERENT. Also par′·ti·zan. [<F <Ital. partigiano, partisano <parte a part <L pars, partis]
—par′ti·san·ship noun