doordetector
nounUK /ˈdɔː dɪˌtɛktə/
US /ˈdɔːr dɪˌtɛktər/
A doordetector is a thing that tells you when someone is at the door.
The doordetector beeped when the mail carrier walked up to the porch.
OTHER MEANINGS
2. A small device that senses when a door opens or closes.
The doordetector on the fridge door warns you if it is left open.
3. A person who is very good at noticing doors and entrances.
As a doordetector, she always spots the hidden side door of a building.
4. A playful name for a pet that runs to the door whenever it hears a knock.
Our dog is a real doordetector and barks before anyone even rings.