/ Dictionary / Index I interplanetary: Meaning and Definition of Find definitions for: in•ter•plan•e•tar•y Pronunciation: (in"tur-plan'i-ter"ē), [key] — adj. being or occurring between the planets or between a planet and the sun. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: interplanetary (Thesaurus) interphone interplant Related Content Daily Word Quiz: fidelity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language