/ Dictionary / Index P planetology: Meaning and Definition of Find definitions for: plan•e•tol•o•gy Pronunciation: (plan"i-tol'u-jē), [key] — n. the branch of astronomy that deals with the physical features of the planets. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. planetoid plane tree 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