(1):

(n.) A protuberance; a swelling; a knob; a button; hence, rising ground; a summit. See Knob, and Knop.

(2):

(v. t.) To strike smartly; to rap; to snap.

(3):

(n.) A sharp blow or slap.

(4):

(v. t.) To bite; to bite off; to break short.

(5):

(v. i.) To make a sound of snapping.