/ Dictionary / Index A astrosphere: Meaning and Definition of Find definitions for: as•tro•sphere Pronunciation: (as'tru-sfēr"), [key] — n. Biol. the central portion of an aster, in which the centrosome lies. the whole aster exclusive of the centrosome. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. astrophysics Astroturf Related Content Daily Word Quiz: fervor Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language