/ Dictionary / Index P proto-form: Meaning and Definition of Find definitions for: pro•to-form Pronunciation: (prō'tō-fôrm"), [key] — n. Ling. a hypothetical linguistic form reconstructed as an element of a protolanguage. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. proto-Elamite protogalaxy 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