n. [ Boom a beam + -kin. See Bumpkin. ] (Naut.) A projecting beam or boom; as: (a) One projecting from each bow of a vessel, to haul the fore tack to, called a tack bumpkin. (b) One from each quarter, for the main-brace blocks, and called brace bumpkin. (c) A small outrigger over the stern of a boat, to extend the mizzen. [ Written also boomkin. ] [ 1913 Webster ]