the ratio of the diameter of a lens, especially a camera lens, to the focal length; the reciprocal of the f number or focal ratio of the lens.
(photog) the ratio of the equivalent focal length of a lens to the effective aperture of the lens; written as f/n, f:n, or fn, where n is the numerical value of this ratio and is equivalent to the f-number
- Relative atomic mass
noun 1. the ratio of the average mass per atom of the naturally occurring form of an element to one-twelfth the mass of an atom of carbon-12 Ar, r.a.m. Former name atomic weight relative atomic mass (rěl’ə-tĭv) See atomic weight.
noun, Navigation. 1. the bearing of an object, relative to the heading of a vessel or aircraft.
noun 1. a subordinate clause introduced by a relative pronoun, adjective, or adverb, either expressed or deleted, especially such a clause modifying an antecedent, as who saw you in He’s the man who saw you or (that) I wrote in Here’s the letter (that) I wrote.
noun, Mathematics. 1. the set of elements contained in a given set that are not elements of another specified set.