/ Dictionary / Index H helio: Meaning and Definition of Find definitions for: he•li•o Pronunciation: (hē'lē-ō"), [key] — pl. -li•os. a heliogram. a heliograph. helio- Pronunciation: [key] a combining form meaning “sun,” used in the formation of compound words: heliolatry. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Heligoland heliocentric Related Content Daily Word Quiz: meritocracy Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language