Trap-door

She then went to look into the mouse-trap, where she found six mice, all alive. She ordered Cinderella to lift the trap-door, when, giving each mouse, as it went out, a little tap with her wand, it was that moment turned into a fine horse, and the six mice made a fine set of six horses of a beautiful mouse-colored, dapple gray.

Source: tatoeba (6211662)

Your garret-windows therefore ſhould always be ſecured, and trap-doors opening to the leads well bolted.

Source: wiktionary

A bell tinkles, and forthwith the trap-doors beneath the stage open and a variety of musical instruments, followed by an equally diversified assortment of heads, are thrust through.

Source: wiktionary

It was reached by a trap-door in the middle of the floor, from which a ladder led down into the small, dark hole.

Source: wiktionary