/ Dictionary / Index W watt-second: Meaning and Definition of Find definitions for: watt-sec•ond Pronunciation: (wot'sek'und), [key] — n. a unit of energy equal to the energy of one watt acting for one second; the equivalent of one joule. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: watt-second (Thesaurus) Watts-Dunton Watusi Related Content Daily Word Quiz: pristine Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language