/ Dictionary / Index A arc spectrum: Meaning and Definition of Find definitions for: arc' spec"trum Pronunciation: [key] — Physics. Physics. a spectrum formed from the light produced by an electric arc, characteristic of the gas or vapor through which the arc passes. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. arc sine arc tan Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language