/ Thesaurus / A Synonyms of action spectrum Find synonyms for: Noun1. action spectrum, spectrumusage: the efficiency with which electromagnetic radiation produces a photochemical reaction plotted as a function of the wavelength of the radiationWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: eccentric Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language