What's the name of the type of button that you have to press and hold for current to pass through it?
A momentary switch has to be held down. This is normal for something like a microswitch or push-button, but is unusual and has to be specified for a lever switch.

This is in contrast to a latching switch, which is operated from one position to another. This is normal for a lever switch, can be found in push-buttons if specified, and is not found in microswitches.