/ Dictionary / Index P protero-: Meaning and Definition of Find definitions for: protero- Pronunciation: [key] a combining form meaning “earlier,” “before,” “former,” used in the formation of compound words: proterotype. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. proteose proterotype 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