/ Dictionary / Index H helianthus: Meaning and Definition of Find definitions for: he•li•an•thus Pronunciation: (hē"lē-an'thus), [key] — pl. -thus•es. any composite plant of the genus Helianthus, comprising the sunflowers. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: helianthus (Thesaurus) helianthine B heliborne 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