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definitions

film speed

noun Photography.
  1. speed(def 5a).

Origin of film speed

First recorded in 1910–15
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for film speed

film speed

noun
  1. the sensitivity to light of a photographic film, specified in terms of the film's ISO rating
  2. the rate at which the film passes through a motion picture camera or projector
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012