transcription, транскрипция: [ ˈap-ə(r)-ˌchu̇r, -chər, -ˌtyu̇r, -ˌtu̇r ]
noun
Etymology: Middle English, from Latin apertura, from apertus, past participle of aperire to open
Date: 15th century
1. : an opening or open space : hole
2.
a. : the opening in a photographic lens that admits the light
b. : the diameter of the stop in an optical system that determines the diameter of the bundle of rays traversing the instrument
c. : the diameter of the objective lens or mirror of a telescope