/ Dictionary / Index T thundercloud: Meaning and Definition of Find definitions for: thun•der•cloud Pronunciation: (thun'dur-kloud"), [key] — n. cumulonimbus. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: thundercloud (Thesaurus) thunderclap thunder egg Related Content Daily Word Quiz: clairvoyant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language