aperture
n. countable C1 Advanced US //ˈæpɝtʃɝ// UK //ˈæpətʃɐ// aper·ture
n. the opening in a camera lens that controls how much light enters. You adjust it to change the brightness or the focus of your photo.
n. the adjustable opening in a camera lens that regulates the amount of light reaching the sensor or film. In optics, it refers to the diameter of a beam of light that is actually admitted by a lens or mirror.
A wide aperture lets in more light.
She opened the aperture to capture the dimly lit stage performance.
The photographer widened the aperture to blur the background, creating a soft, dreamlike effect around the subject.
From late Middle English, from Latin apertūra (“an opening”), from aperiō (“to uncover, make or lay bare”) + -tūra (“-ure”, action noun suffix). Doublet of overture.