/ Dictionary / Index P protochordate: Meaning and Definition of Find definitions for: pro•to•chor•date Pronunciation: (prō"tō-kôr'dāt), [key] — n. Zool. any of the nonvertebrate chordates, as the tunicates, cephalochordates, and hemichordates. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. protoavis protocol 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