aperture

US /ˈæp.ɚ.tʃɚ/
UK /ˈæp.ɚ.tʃɚ/
"aperture" picture
1.

開口部, 穴, 絞り

a small opening or hole, especially one through which light or air may pass

:
The camera's aperture controls the amount of light entering the lens.
カメラの絞りはレンズに入る光の量を制御します。
There was a small aperture in the wall, allowing us to peek through.
壁には小さな開口部があり、そこから覗くことができた。