aperture
//ˈæp.ə.tʃər//
Noun
apertureSingular
aperturesPlural
1
An opening, hole, or gap, especially one that allows light to pass through.
Light entered the room through a small aperture in the wall.
2
The adjustable opening in a camera lens that controls the amount of light reaching the film or sensor.
I adjusted the aperture to let more light into the camera.
3
In optics and astronomy, the diameter of the light-collecting element of a telescope or other optical instrument.
A telescope with a larger aperture can gather more light and reveal fainter stars.