Entry 2 senses · 2 variants Webster, 1913 Defoliate · De·fo·li·ate · IPA /diːˈfəʊliː(j)eɪt/ a. v. t. 01 a. Deprived of leaves, as by their natural fall. 1. Deprived of leaves, as by their natural fall. 02 v. t. to cause (a plant) to shed its leaves. 1. to cause (a plant) to shed its leaves.