/ Dictionary / Index P proline: Meaning and Definition of Find definitions for: pro•line Pronunciation: (prō'lēn, -lin), [key] — n. Biochem. an alcohol-soluble amino acid, CHNHCOOH, occurring in high concentration in collagen. Abbr.: Pro; Symbol: P Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: proline (Thesaurus) prolific prolix 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