buttonbulb
nounUK /ˈbʌtənbʌlb/
US /ˈbʌtənbʌlb/
A buttonbulb is a small round light that you push to turn on.
She pressed the buttonbulb and the little lamp lit up.
OTHER MEANINGS
2. A tiny bulb-shaped button on a machine or toy.
He pressed the buttonbulb to start the toy robot.
3. A small glowing dot on a screen that you can tap.
Tap the buttonbulb on the screen to open the game.
4. A round knob that lights up when you touch it.
The buttonbulb on the door glowed red at night.