/ Dictionary / Index H heliosphere: Meaning and Definition of Find definitions for: he•li•o•sphere Pronunciation: (hē'lē-u-sfēr"), [key] — n. Astron. the region around the sun over which the effect of the solar wind extends. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: heliosphere (Thesaurus) helioscope heliostat Related Content Daily Word Quiz: cygnet Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language