Source : Webster's Revised Unabridged Dictionary (1913)

Bumkin \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}.]