Bum"kin (&?;), 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.]