Source : Webster's Revised Unabridged Dictionary (1913)

Belaying pin \Be*lay"ing pin`\ (b[-e]*l[=a]"[i^]ng p[i^]n`).
   (Naut.)
   A strong pin in the side of a vessel, or by the mast, round
   which ropes are wound when they are fastened or belayed.

Source : WordNet®

belaying pin
     n : a wood or metal bar to which a rope can be secured (as on a
         ship or in mountain climbing)