knocker

noun

1. a device (usually metal and ornamental) attached by a hinge to a door

Synonym: doorknockerrapper

2. either of two soft fleshy milk-secreting glandular organs on the chest of a woman

Synonym: breastbosomboobtittitty

3. one who disparages or belittles the worth of something

Synonym: detractordisparagerdepreciator

4. a person who knocks (as seeking to gain admittance)

e.g. open the door and see who the knocker is

5. (Yiddish) a big shot who knows it and acts that way
a boastful immoderate person

1. （固定在门上供敲门用的）门环
A knocker is a piece of metal on the front door of a building, which you use to hit the door in order to attract the attention of the people inside.

1. 上门推销员：上门服务door-to-door service | 上门推销员knocker | 商品步行街shopping mall

2. 门环：knocked down frame 可拆卸的门框 | knocker 门环 | knot 结

3. 挑剔的人：knob 按钮 | knocker 挑剔的人 | knowability 可知性

4. 敲门者：knocked-down 未装配的 | knocker 敲门者 | knocking 爆震音