One that is united or associated with another or others in an activity or a sphere of common interest, especially: A member of a business partnership. A spouse. A domestic partner. See Usage Note at domestic partner. Either of two persons dancing together. One of a pair or team in a sport or game, such as tennis or bridge. Nautical A wooden framework used to strengthen a ship's deck at the point where a mast or other structure passes through it. Often used in the plural. To make a partner of. To bring together as partners. To be the partner of. To work or perform as a partner or partners.