from
The Collaborative International Dictionary of English v.0.48
knocker \knock"er\, n.
1. One who, or that which, knocks; specifically, an
instrument, or kind of hammer, fastened to a door, to be
used in seeking for admittance.
[1913 Webster]
Shut, shut the door, good John ! fatigued, I said;
Tie up the knocker; say I'm sick, I'm dead. --Pope.
[1913 Webster]
2. A person strikingly handsome, beautiful, or fine; one who
wins admiration; a "stunner." [Slang.]
[Webster 1913 Suppl.]
3. A species of large cockroach, especially {Blabera
gigantea}, of semitropical America, which is able to
produce a loud knocking sound.
[Webster 1913 Suppl.]
4. [usually used in pl.] a woman's breast. [vulgar]
[PJC]