What is an alternative name for the theatrical 'trap-door'?

Question:It's called a "scruto".

Best Answer - Chosen by Asker: It's called a "scruto".

hole

I've heard it called "the lift"

I've most often heard it called a "Trap"

A "scruto" is a movable floor, and the word is used for the trap as well.

Corner Trap - conveying a single standing figure.
Star Trap - Projects actor onto stage at great speed.
Grave Trap - Approx 6ft x 3ft (Grave sized).
There are also:
Bristle trap, cauldron trap, footlights trap, ghost glide, slote, vamp trap.