1. To change the nature or natural qualities of. 2. To render unfit to eat or drink without destroying usefulness in other applications, especially to add methanol to (ethyl alcohol). 3. To alter the structure of (a protein), as with heat, alkali, or acid, so that some of its original properties, especially its biological activity, are diminished or eliminated. 4. To add nonfissionable matter to (fissionable material) so as to prevent use in an atomic weapon.
