/ Dictionary / Index P protoplast: Meaning and Definition of Find definitions for: pro•to•plast Pronunciation: (prō'tu-plast"), [key] — n. the contents of a cell within the cell membrane, considered as a fundamental entity. the primordial living unit or cell. a person or thing that is formed first; original; prototype. the hypothetical first individual or one of the supposed first pair of a species or the like. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: protoplast (Thesaurus) protoplasm protopodite Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language