/ Dictionary / Index P phytoalexin: Meaning and Definition of Find definitions for: phy•to•a•lex•in Pronunciation: (fī"tō-u-lek'sin), [key] — n. Biochem. any of a class of plant compounds that accumulate at the site of invading microorganisms and confer resistance to disease. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. phyto- phytobiology Related Content Daily Word Quiz: tactful Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language