/ Dictionary / Index P protolanguage: Meaning and Definition of Find definitions for: pro•to•lan•guage Pronunciation: (prō'tō-lang"gwij), [key] — n. Ling. the reconstructed or postulated parent form of a language or a group of related languages. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. proto-Ionic protolithic 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