phy·to·chemical I. \"ˌ\adjective Etymology:phyt- + chemical (I) : of, relating to, or being phytochemistry • phy·to·chemically\"ˌ \adverb II. noun Etymology:phyt- + chemical (II) : a chemical compound (as beta-carotene or isothiocyanate) occurring naturally in plants < promoted the health benefits of phytochemicals >