doorknocker
Longman Dictionary of Contemporary English 5++LDOCE 5++door·knock·er /ˈdɔːˌnɒkə $ ˈdɔːrˌnɑːkər/ (also knocker) noun [countable] DHHa heavy metal ring or bar on a door that you use to knock with 门环，敲门器
Examples from the Corpus
doorknocker• On it were a variety of jugs and china vases from the same school of design as the pixie doorknocker.door·knock·er nounChineseSyllable
bar or heavy metal Corpus on door a ring a
doorknocker
door‧knock‧er /ˈdɔːˌnɒkə $ ˈdɔːrˌnɑːkər/
(also knocker) noun [countable]
a heavy metal ring or bar on a door that you use to knock with
door‧knock‧er /ˈdɔːˌnɒkə $ ˈdɔːrˌnɑːkər/
(also knocker) noun [countable]a heavy metal ring or bar on a door that you use to knock with