knocker

A knocker is most often the metal piece on a door that you lift and let fall to make a sound. It can also mean a person who knocks at doors, especially someone who goes from place to place trying to sell something or ask for something. In informal British and Australian English, it can also mean a person who keeps criticizing things. So when you hear the word, the setting usually tells you whether it means door hardware, a caller at the door, or a fault-finder.

The word "knocker" has a few clear meanings that all grow out of the idea of knocking. Most people first think of the metal piece fixed to a door. You lift it, let it fall, and it hits the door or a plate to announce that you have arrived. Many old houses have decorative ones, so the word can bring to mind something practical but also a little traditional or elegant.

The word also extends beyond the object itself. A knocker can be a person who knocks at doors, especially in the sense of someone calling from house to house, such as a salesperson, collector, or campaign worker. In that use, it can sound slightly negative, because it may suggest an unwanted visitor who keeps turning up at the door.

There is also a figurative meaning. In informal British and Australian English, a knocker is someone who is always putting people or ideas down. In other words, it means a habitual critic or fault-finder. This sense comes from the verb "to knock," which can mean to criticize.

So the word can point to three main ideas: the thing on the door, the person at the door, and the person who keeps criticizing. The context usually makes the meaning clear.