knocker

UK: /ˈnɒkə^r/ US: /ˈnɑkɚ/ ,(nok′ər)

WordReference Random House Learner's Dictionary of American English © 2025

knock•er /ˈnɑkɚ/   n. [countable]

1. someone or something that knocks.
2. a hinged knob, bar, etc., on a door, to use for knocking.

WordReference Random House Unabridged Dictionary of American English © 2025

knock•er  (nok′ər), n. 

1. a person or thing that knocks.
2. a hinged knob, bar, etc., on a door, for use in knocking.
3. Informal Terms a persistent and carping critic;
   faultfinder.
4. Slang Terms (vulgar). a female breast.
5. British Terms, Idioms on the knocker, canvassing or selling door-to-door.

• 1350–1400; Middle English; see knock, -er¹

Collins Concise English Dictionary © HarperCollins Publishers::

knocker / ˈnɒkə/ noun

1. an object, usually ornamental and made of metal, attached to a door by a hinge and used for knocking
2. a person who finds fault or disparages
3. (usually plural) a female breast
4. a person or thing that knocks
5. on the knocker ⇒ promptly; at once: you pay on the knocker here