n. One who shares or takes part in anything; a sharer or partaker: as, to be a partner in one's joys and sorrows.n. One who is associated with another or others; an associate.n. One who is associated with another in some game or amusement: One who plays on the same side, as, specifically, in whist. One who dances with another, especially one of the opposite sex.n. One who is associated in marriage with another of the opposite sex; a husband or wife.n. One who is associated with another or others as a principal or the contributor of capital in a business or joint adventure, and usually shares its risks and profits. See partnership.n. pl. Naut., pieces of timber let in between two deck-beams, to form a framing for the support of anything which passes through a vessel's deck, as masts, capstan, or pumps.n. 1 and Friend, Companion, etc. See associate.To join; associate as a partner.n. In an involution, the element coupled with a given element.