/ Dictionary / Index M molecular spectrum: Meaning and Definition of Find definitions for: molec'ular spec'trum Pronunciation: [key] the spectrum of light emitted or absorbed by a species of molecule. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. molecular sieve molecular weight Related Content Daily Word Quiz: jugular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language