English Reference
noun

aperture

n.
US /ˈæpɝtʃɝ/ UK /ˈæpətʃɐ/ aper·ture UK spelling apertures

  1. 01 B2 Upper Intermediate Technical Science

    the opening in a camera lens that you can make wider or narrower to control the amount of light.

    the variable opening in an optical system, such as a camera lens, that determines the amount of light admitted to the focal plane.

    Simple

    If you use a wider aperture, your photos will have a blurry background.

    In context

    The photographer adjusted the aperture to f/2.8 to achieve a shallow depth of field for the portrait session.

    Usage

    Often used with the verbs 'widen', 'narrow', or 'adjust'.

    openingf stop
  2. 02 C1 Advanced Formal

    a small or narrow hole, gap, or opening in a surface.

    a physical opening, hole, or gap through which light or matter may pass.

    Simple

    A tiny aperture in the wall allowed a thin beam of light into the dark cave.

    In context

    The researchers measured the precise dimensions of the aperture to ensure the gas could flow through the valve at a constant rate.

    Usage

    Commonly used in technical or scientific descriptions of structures.

  3. 03 C2 Proficiency Technical Science

    the large dish or part of a satellite that sends and receives radio signals.

    the effective area of an antenna that receives or transmits radio frequency energy.

    Simple

    The satellite's large aperture allows it to send data across the ocean.

    In context

    Engineers designed a synthetic aperture radar to provide high-resolution imagery regardless of weather conditions or time of day.

Social media offered a much broader aperture, and after the pandemic, many platforms got rid of fact-checkers and pulled back from policing health claims, leaving more room for misinformation.

Smithsonian Magazine· 9 Sept 2026

He used a refracting  telescope with a 2.4-inch aperture and exposed a daguerreotype plate for 84 seconds as the moon passed in front of the sun.

Smithsonian Magazine· 28 Jul 2026

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.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Latin apertūra
Level C1 · Advanced
Frequency Frequent
Updated