Definition of partisan

• n. - An adherent to a party or faction; esp., one who is strongly and passionately devoted to a party or an interest.
• n. - The commander of a body of detached light troops engaged in making forays and harassing an enemy.
• n. - Any member of such a corps.
• a. - Adherent to a party or faction; especially, having the character of blind, passionate, or unreasonable adherence to a party; as, blinded by partisan zeal.
• a. - Serving as a partisan in a detached command; as, a partisan officer or corps.
• n. - A kind of halberd or pike; also, a truncheon; a staff.