aperture
(noun) an man-made opening; usually small
aperture
(noun) a device that controls amount of light admitted
aperture
(noun) a natural opening in something
Source: WordNet® 3.1
aperture (plural apertures)
An opening, gap, or hole, usually small and narrow
(optics) Something which restricts the diameter of the light path through one plane in an optical system.
(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.
(spaceflight, communications) 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.
(mathematics, rare, of a right circular cone) The maximum angle between the two generatrices.
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.
Source: Wiktionary
Ap"er*ture, n. Etym: [L. apertura, fr. aperire. See Aperient.]
1. The act of opening. [Obs.]
2. An opening; an open space; a gap, cleft, or chasm; a passage perforated; a hole; as, an aperture in a wall. An aperture between the mountains. Gilpin. The back aperture of the nostrils. Owen.
3. (Opt.)
Definition: The diameter of the exposed part of the object glass of a telescope or other optical instrument; as, a telescope of four-inch aperture.
Note: 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 100Âş aperture.
Source: Webster’s Unabridged Dictionary 1913 Edition
2 April 2025
(adjective) secret or hidden; not openly practiced or engaged in or shown or avowed; “covert actions by the CIA”; “covert funding for the rebels”
The world’s most expensive coffee costs more than US$700 per kilogram. Asian palm civet – a cat-like creature in Indonesia, eats fruits, including select coffee cherries. It excretes partially digested seeds that produce a smooth, less acidic brew of coffee called kopi luwak.
