/ Dictionary / Index P proinsulin: Meaning and Definition of Find definitions for: pro•in•su•lin Pronunciation: (prō-in'su-lin, -ins'yu-), [key] — n. Biochem. the prohormone of insulin, converted into insulin by enzymatic removal of part of the molecule. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. prohormone project Related Content Daily Word Quiz: feline Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language