/ Dictionary / Index P pluton: Meaning and Definition of Find definitions for: plu•ton Pronunciation: (pl'ton), [key] — n. Geol. any body of igneous rock that solidified far below the earth's surface. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: pluton (Thesaurus) plutocratic Plutonian Related Content Daily Word Quiz: simian Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language