Aperture
//ˈap.ə.t͡ʃə// noun
noun ·Moderate ·High school level
Definitions
Noun
- 1 A small or narrow opening, gap, slit, or hole.
"an aperture in a wall"
- 2 an man-made opening; usually small wordnet
- 3 A hole which restricts the diameter of the lightpath through one plane in an optical system.
- 4 a device that controls amount of light admitted wordnet
- 5 A hole which restricts the diameter of the lightpath through one plane in an optical system.; The diameter of such a hole which restricts the width of the lightpath through the whole system. For a telescope, this is the diameter of the objective lens.
"This telescope has a 100 cm aperture."
Show 3 more definitions
- 6 a natural opening in something wordnet
- 7 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.
- 8 The maximum angle between the two generatrices. rare
"If the generatrix makes an angle θ to the axis, then the aperture is 2θ."
Example
More examples"What is the correct aperture in this light?"
Etymology
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.
Related phrases
More for "aperture"
Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.