denature

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To change the nature or natural qualities of.
2. v. To render unfit to eat or drink without destroying usefulness in other applications, especially to add methanol to (ethyl alcohol).
3. v. Biochemistry To cause the tertiary structure of (a protein) to unfold, as with heat, alkali, or acid, so that some of its original properties, especially its biological activity, are diminished or eliminated.
4. v. Biochemistry To cause the paired strands of (double-stranded DNA) to separate into individual single strands.
5. v. Physics To add nonfissionable matter to (fissionable material) so as to prevent use in an atomic weapon.

Century Dictionary and Cyclopedia

1. Same as denaturize.

Wiktionary

1. v. To take away a natural characteristic or inherent property of a thing or a person.
2. v. in reference to alcohol to add something that makes alcohol unsuitable for consumption but leaves the alcohol suitable for other purposes.
3. v. chemistry To subject (especially a protein) to conditions altering its original form or state.
4. v. To combine fissionable material with nonfissionable material in order to prevent its use in an atomic weapon.

GNU Webster's 1913

1. v. To deprive of its natural qualities; change the nature of.
2. v. to render (ethyl alcohol) unfit to drink by adding in toxic or unpalatable substances (such as benzene or pyridine) which nevertherless permit alcohol to be used as a solvent.
3. v. modify the tertiary structure of (a protein or nucleic acid) so as to reduce or destroy its characteristic biological activity.
4. v. To become denatured.

WordNet 3.0

1. v. modify (as a native protein) especially by heat, acid, alkali, or ultraviolet radiation so that all of the original properties are removed or diminished
2. v. make (alcohol) unfit for drinking without impairing usefulness for other purposes
3. v. add nonfissionable material to (fissionable material) so as to make unsuitable for use in an atomic bomb