knocker

noun13

1. •
   A device, usually hinged with a striking plate, used for knocking on a door.

   • Knockers in this part of the world seem intended for ornament only, — nobody seems to pay any attention to them when they’re used. — 1897
2. •
   [usually plural] (slang, vulgar) A person's breast, especially if large.
3. •
   A critic; one who disparages.

   • "I try to give everybody credit," declared the old man. "I am not a knocker. I am not too good for this world." — 1947
4. •
   (informal) A person who knocks (denigrates) something.
5. •
   A person who knocks.

   • He was a loud knocker. Despite my usual timidity, after a bit I opened the door. — 1963
6. •
   (slang) A gun.

   • Lay down on that 'Tussin, I think I'ma snooze (Like, like what?) We keep knockers like this shit essential .22 long rifles, these bullets like pencils Homicide, bodies drop when we bend through — 2021
7. •
   (slang, old-fashioned) A person who is strikingly handsome or otherwise admirable; a stunner.
8. •
   A mechanical device in a pinball table that produces a loud percussive noise to signal that a free game has been earned.

   • A good game needs color, lights, bells, gongs, and knockers, all to assure the player he is making progress[…] — 1963
9. •
   (slang) An undercover policeman.

   • The knockers around better do what I say so — 2019
10. •
    A large cockroach, especially Blaberus giganteus, of semitropical America, which is able to produce a loud knocking sound.
11. •
    (slang) One who defaults on payment of a wager.

    • To the consternation of those who believed that bookies were 'knockers' (defaulters), he paid his losses with alacrity […] — 2004
12. •
    A large, boulder-shaped outcrop of bedrock in an otherwise low-lying landscape, chiefly associated with a mélange.
13. •
    (no longer used) A dwarf, goblin, or sprite imagined to dwell in mines and to indicate the presence of ore by knocking.