/ Dictionary / Index P -plast: Meaning and Definition of Find definitions for: -plast Pronunciation: [key] a combining form meaning “living substance,” “organelle,” “cell,” used in the formation of compound words: chloroplast; chromoplast; protoplast. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Plassey plaster Related Content Daily Word Quiz: fervor Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language