aperture

Example:The opening in the wall allowed the thief to enter the house.

Definition:A space or entry through a barrier, wall, or other structure.

Example:There was a hole in the tent door, which let in the cold breeze.

Definition:An opening, usually round, made by piercing something, particularly one where something can pass through.

Example:The orifice in the pipe was used to regulate the flow of water.

Definition:A small opening or hole in a wall, valve, or other structure, especially to let food, gas, liquid, or air through.