from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A camera lens aperture setting that corresponds to an f-number.
- n. See f-number.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Any of the discrete steps or stopping points for adjusting the aperture of a lens, either marked on a ring on the lens and adjusted by rotating that ring or marked in the display of a digital camera and adjusted by buttons or touch-sensitive controls.
f(ocal length) + stop.(American Heritage® Dictionary of the English Language, Fourth Edition)