fertilize Syllabification: (fer·ti·lize)Pronunciation: /ˈfərtlˌīz/Translate fertilize | into French | into German | into Italian | into Spanish Definition of fertilize verb [with object] cause (an egg, female animal, or plant) to develop a new individual by introducing male reproductive material. make (soil or land) more fertile or productive by adding suitable substances to it. Derivatives fertilizable adjective fertilize in other Oxford dictionaries Definition of fertilize in the British & World English dictionary