How to say "aperture" in Japanese

• 隙間すきまJLPT N2approx.Common
  nounCovers an unintended gap, crack, or crevice between things. If by 'aperture' you mean a leak or narrow opening left by accident, this fits; for photographic or optical apertures it is not the word you want.
  歯はが抜ぬけて隙間すきまが空あいていた。↗

  His teeth had gaps.
• 口径こうけいCommon
  nounRefers to the measured diameter of an opening, especially of lenses, tubes, or barrels, hence 'bore' and 'calibre'. Use it when 'aperture' means the size or width of the opening rather than the opening itself.
• 開口かいこうCommon
  noun, suru verb, intransitive verbDenotes the aperture as an opening, including that of a camera. Use it for the aperture as a physical or optical opening; it pairs with the technical sense of the English word.
• しぼりCommon
  nounThe aperture of a camera in practice, i.e. the adjustable aperture stop that controls how much light enters. Use this when talking about photographic settings such as widening or narrowing the aperture.
  この明あかるさで絞しぼりはどのくらいですか。↗

  What is the correct aperture in this light?

For photography and optics use 口径 for physical diameter, 開口 for the opening itself, and 「しぼり」 for the adjustable stop; use 隙間 only for an incidental gap or crevice, not technical senses.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 隙間すきまgap
• 口径こうけいaperture
• 開口かいこうopening
• アパーチャaperture
• 開き口ひらきぐちaperture
• 開口部かいこうぶaperture
• 開度かいどdivergence
• 空隙くうげきvacant space
• 穴隙けつげきcrevice
• 窓付きまどつきwindow (e.g. in an envelope, box, etc.)
• しぼりaperture