/ Dictionary / Index H heliotaxis: Meaning and Definition of Find definitions for: he•li•o•tax•is Pronunciation: (hē"lē-ō-tak'sis), [key] — n. Biol. movement of an organism toward or away from sunlight. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. heliostat heliotherapy Related Content Daily Word Quiz: impetuous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language