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See also: aperturé




From Latin apertūra (opening), from apertus, past participle of aperīre (to open, uncover), opposed to operīre (to close, cover). See aperient.



aperture (plural apertures)

  1. An opening; an open space; a gap, cleft, or chasm; a passage perforated; a hole
    an aperture in a wall
    • 1860, Samuel Hannaford, Sea and River-side Rambles in Victoria Chapter 7
      In the centre of the fleshy membrane is an aperture leading into a deep cavity, at the bottom of which is placed a prominent piston that may be retracted by muscular fibres provided for the purpose.
    • Owen
      the back aperture of the nostrils
  2. (optics) Something which restricts the diameter of the light path through one plane in an optical system.
  3. (astronomy, photography) The diameter of the aperture (in the sense above) which restricts the width of the light path through the whole system. For a telescope, this is the diameter of the objective lens.
    This telescope has a 100cm aperture.
  4. (spaceflight, communication) The (typically) large-diameter antenna used for receiving and transmitting radio frequency energy containing the data used in communication satellites, especially in the geostationary belt. For a comsat, this is typically a large reflective dish antenna; sometimes called an array.
  5. (mathematics, rare, of a right circular cone) The maximum angle between the two generatrices.
    If the generatrix makes an angle θ to the axis, then the aperture is 2θ.

Usage notesEdit

The aperture of microscopes is often expressed in degrees, called also the angular aperture, which signifies the angular breadth of the pencil of light which the instrument transmits from the object or point viewed; as, a microscope of 100° aperture.

Derived termsEdit

Related termsEdit


Further readingEdit




aperture f

  1. plural of apertura





  1. vocative masculine singular of apertūrus




  1. First-person singular (yo) present subjunctive form of aperturar.
  2. Formal second-person singular (usted) present subjunctive form of aperturar.
  3. Third-person singular (él, ella, also used with usted?) present subjunctive form of aperturar.
  4. Formal second-person singular (usted) imperative form of aperturar.