/ Dictionary / Index P prohormone: Meaning and Definition of Find definitions for: pro•hor•mone Pronunciation: (prō-hôr'mōn), [key] — n. Biochem. the inactive precursor molecule from which a hormone is derived. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. prohibitory proinsulin 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