1. A fervent, sometimes militant supporter or proponent of a party, cause, faction, person, or idea. 2. A member of an organized body of fighters who attack or harass an enemy, especially within occupied territory; a guerrilla.
ADJECTIVE:
1. Of, relating to, or characteristic of a partisan or partisans. 2. Devoted to or biased in support of a party, group, or cause: partisan politics.
ETYMOLOGY:
French, from Old French, from Old Italian dialectal partisano, variant of Old Italian partigiano, from parte, part, from Latin pars, part-. See part.