(1):
(n.) A person strikingly handsome, beautiful, or fine; one who wins admiration; a "stunner."
(2):
(n.) A species of large cockroach, esp. Blabera gigantea, of semitropical America, which as able to produce a loud knocking sound.
(3):
(n.) One who, or that which, knocks; specifically, an instrument, or kind of hammer, fastened to a door, to be used in seeking for admittance.