a bell or other sounding device, actuated by a push button at an outer door; the push button activating the bell; alos, the ringing of such a bell; as, I was in the shower and didn't hear the doorbell.

a push button at an outer door that gives a ringing or buzzing signal when pushed

Electrical device at the entrance door, which when pressed, sounds a bell or buzzer inside the home or office to announce visitors.

A doorbell is a signaling device commonly found near a door.