button

/ˈbʌtən/ noun [C]

Definition

› COMMUNICATIONS, IT a small, often circular object which you press to operate a device or a machine, or an area on a computer screen which looks and works like one of these: press/hit/push a button Press the green button to start the machine and the red button to stop it.the send/save/delete button Always re-read your email messages carefully before you hit the send button.

› MARKETING button ad

(Definition of button noun from the Cambridge Business English Dictionary © Cambridge University Press)