/ Dictionary / Index M mantle rock: Meaning and Definition of Find definitions for: man'tle rock" Pronunciation: [key] the layer of disintegrated and decomposed rock fragments, including soil, just above the solid rock of the earth's crust; regolith. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. mantle plume mantlet Related Content Daily Word Quiz: nonchalant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language