deadbutton

2. A button on a website or app that looks clickable but does nothing.

Users got frustrated when the sign-up deadbutton ignored their clicks.

3. A person in a group who never reacts or contributes, like a switched-off control.

At the meeting, he was the deadbutton who said nothing the whole time.

4. A placeholder button left in a design or prototype before the real function is built.

The mock-up still had a deadbutton where the checkout link would go.