/ Dictionary / Index P planetary: Meaning and Definition of Find definitions for: plan•e•tar•y Pronunciation: (plan'i-ter"ē), [key] — adj. of, pertaining to, or resembling a planet or the planets. wandering; erratic. terrestrial; global. noting or pertaining to an epicyclic gear train in which a sun gear is linked to one or more planet gears also engaging with an encircling ring gear. —n. a planetary gear train. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: planetary (Thesaurus) planetarium planetary nebula Related Content Daily Word Quiz: immense Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language