the speech act of answering an attack on your assertions; "his refutation of the charges was short and persuasive"; "in defense he said the other man started it"
make (alcohol) unfit for drinking without impairing usefulness for other purposes
modify (as a native protein) especially by heat, acid, alkali, or ultraviolet radiation so that all of the original properties are removed or diminished
add nonfissionable material to (fissionable material) so as to make unsuitable for use in an atomic bomb