aperture
/ˈæp.ɚˌt͡ʃʊɹ/ noun C1- A small or narrow opening, gap, slit, or hole. · an aperture in a wall
- 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.
- 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.
Plural apertures
From the library
In an instant Beppo, a skilful workman, made a small hole in the wet plaster, dropped in the pearl, and with a few touches covered over the aperture once more.
Over the edge there peeped a clean-cut, boyish face, which looked keenly about it, and then, with a hand on either side of the aperture, drew itself shoulder-high and waist-high, until one knee rested upon the edge.
The ejaculation had been drawn from my companion by the fact that our door had been suddenly dashed open, and that a huge man had framed himself in the aperture.
Edmond was obliged to assist him, for otherwise he would not have been able to enter by the small aperture which led to Dantès’ chamber.
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