A part of a plant. A distinct part of a whole, especially: Linguistics A syntactic unit of a sentence; a clause. Logic A proposition of a syllogism. Mathematics An element in a set. A part or an organ of a human or animal body, as: A limb, such as an arm or a leg. The penis. One that belongs to a group or an organization: a club member; a bank that is a member of the FDIC. Mathematics The expression on either side of an equality sign. A structural unit, such as a beam or wall.