transitive verb denatured -·tured, denaturing -·tur·ing

1. to change the nature of; take natural qualities away from
2. to make (alcohol, etc.) unfit for human consumption without spoiling for other uses
3. to change the structure of (a protein) by heat, acids, alkalies, etc., so that the original properties are greatly changed or eliminated
4. to add a nonfissionable isotope to (a fissionable isotope) so that the mixture cannot be used in nuclear bombs but can still be used as fuel material

Etymology: ML denaturare: see de- & nature