lastbutton
nounUK /ˈlɑːstˌbʌtən/
US /ˈlæstˌbʌtən/
The last button is the final button you press or fasten.
She pressed the lastbutton to finish the game.
OTHER MEANINGS
2. The button at the very bottom of a row of buttons.
The lastbutton on his coat was missing.
3. The final step or choice that completes something.
Saying yes was the lastbutton in their plan.
4. The button you press to end a machine or program.
Press the lastbutton to turn off the toy.