- an opening, as a hole, slit, crack, gap, etc.
- Also called aperture stop. Optics. an opening, usually circular, that limits the quantity of light that can enter an optical instrument.
- a hole, gap, crack, slit, or other opening
- a usually circular and often variable opening in an optical instrument or device that controls the quantity of radiation entering or leaving it
- the diameter of such an openingSee also relative aperture
early 15c., from Latin apertura “an opening,” from apertus, past participle of aperire “to open” (see overt).
- An opening, such as a hole, gap, or slit.
- A usually adjustable opening in an optical instrument, such as a microscope, a camera, or a telescope, that limits the amount of light passing through a lens or onto a mirror.
- The diameter of such an opening.
- The diameter of the objective of a telescope or microscope.