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.
名词（固定在门上供敲门用的）门环；吹毛求疵的人；一味批评的人；奶子网络挨户敲门的推销员；敲击者；敲门者
