1 a metal or wooden instrument hinged to a door for knocking to call attention.
2 a person or thing that knocks.
3 (in pl.) coarse sl. a woman's breasts.
4 a person who buys or sells door to door.
Phrases and idioms:
knocker-up Brit. hist. a person employed to rouse early workers by knocking at their doors or windows. on the knocker
1 a (buying or selling) from door to door. b (obtained) on credit.
2 Austral. & NZ colloq. promptly. up to the knocker Brit. sl. in good condition; to perfection.
Useful english dictionary. 2012.