doorbuzzer
nounUK /ˈdɔːˌbʌzə/
US /ˈdɔːrˌbʌzər/
A doorbuzzer is a button you press to make a sound so someone inside knows you are at the door.
She pressed the doorbuzzer and waited for her friend to open the door.
OTHER MEANINGS
2. A device that lets someone inside unlock the door from a distance.
The doorbuzzer clicked, and the front door unlocked.
3. A buzzer used to call a person to the door of a building.
Visitors must use the doorbuzzer to reach apartment 4B.
4. A sound-making button at an entrance that alerts people inside.
The doorbuzzer rang twice before anyone answered.