n.
The ratio of the focal length of a lens or lens system to the effective diameter of its aperture. Also called f-stop.
[F(OCAL LENGTH) + NUMBER.]
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
