9 Grammatical Pitfalls
aperture ap·er·ture (āp'ər-chər)
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.