Source : Webster's Revised Unabridged Dictionary (1913)

Firelock \Fire"lock`\, n.
   An old form of gunlock, as the flintlock, which ignites the
   priming by a spark; perhaps originally, a matchlock. Hence, a
   gun having such a lock.

Source : WordNet®

firelock
     n : a muzzle loader having a flintlock type of gunlock [syn: {flintlock}]