Source : Webster's Revised Unabridged Dictionary (1913)

Forelock \Fore"lock`\, n.
   1. The lock of hair that grows from the forepart of the head.

   2. (Mech.) A cotter or split pin, as in a slot in a bolt, to
      prevent retraction; a linchpin; a pin fastening the
      cap-square of a gun.

   {Forelock bolt}, a bolt retained by a key, gib, or cotter
      passing through a slot.

   {Forelock hook} (Rope Making), a winch or whirl by which a
      bunch of three yarns is twisted into a standard. --Knight.
      

   {To take} {time, or occasion}, {by the forelock}, to make
      prompt use of anything; not to let slip an opportunity.

            Time is painted with a lock before and bald behind,
            signifying thereby that we must take time by the
            forelock; for when it is once past, there is no
            recalling it.                         --Swift.

            On occasion's forelock watchful wait. --Milton.