/ Dictionary / Index I inferior planet: Meaning and Definition of Find definitions for: infe'rior plan'et Pronunciation: [key] — Astron. Astron. either of the two planets whose orbits are inside the orbit of the earth: Venus and Mercury. Cf. superior planet. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. inferior ovary inferior vena cava 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