/ Dictionary / Index H heat lightning: Meaning and Definition of Find definitions for: heat' light"ning Pronunciation: [key] lightning too distant for thunder to be heard, observed as diffuse flashes near the horizon on summer evenings. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. heat lamp Heat-Moon Related Content Daily Word Quiz: rotund Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language