Definition of aperture noun from the Oxford Advanced Learner's Dictionary



    BrE BrE//ˈæpətʃə(r)//
    ; NAmE NAmE//ˈæpərtʃər//
    , also NAmE//ˈæpərtʃʊr//
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  1. 1(formal) a small opening in something The soldier fired the rifle through a narrow aperture in a pile of sandbags. The bell ropes passed through apertures in the ceiling.
  2. 2(specialist) an opening that allows light to reach a lens, especially in cameras For flash photography, set the aperture at f.5.6. Open up the lens aperture to maximize the brightness of the shot. Binoculars of this aperture are very expensive.
  3. Word Originlate Middle English: from Latin apertura, from apert- ‘opened’, from aperire ‘to open’.
See the Oxford Advanced American Dictionary entry: aperture