/ Dictionary / Index P protopectin: Meaning and Definition of Find definitions for: pro•to•pec•tin Pronunciation: (prō"tu-pek'tin), [key] — n. Biochem. any of the class of water-insoluble pectic substances that are found in the rind of citrus fruits or in apple peels and that are hydrolyzed to pectin or pectic acid. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. protopathic protophloem Related Content Daily Word Quiz: wary Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language