VERB (3)

1. add nonfissionable material to (fissionable material) so as to make unsuitable for use in an atomic bomb;

2. modify (as a native protein) especially by heat, acid, alkali, or ultraviolet radiation so that all of the original properties are removed or diminished;

3. make (alcohol) unfit for drinking without impairing usefulness for other purposes;

The Collaborative International Dictionary of English v.0.48:

Denature \De*na"ture\, v. i.
   To become denatured.
   [PJC]

The Collaborative International Dictionary of English v.0.48:

Denature \De*na"ture\, v. t. [De- + nature.]
   To deprive of its natural qualities; change the nature of.
   [Webster 1913 Suppl.]

   2. 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.
      [PJC]

   3. modify the tertiary structure of (a protein or nucleic
      acid) so as to reduce or destroy its characteristic
      biological activity.

   Note: Bioactive macromolecules such as enzymes or DNA may be
         denatured by heat, acid, alkali, or solvent treatment;
         the extent of such treatment required to denature a
         molecule varies with the specific compound. In some
         cases the denatured molecules may regain their original
         properties (renature) by other treatments. Denaturation
         may also cause a change in the physical properties of
         such molecules, e.g. proteins may become insoluble in
         water.
         [PJC]

WordNet (r) 3.0 (2006):

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

Moby Thesaurus II by Grady Ward, 1.0:

90 Moby Thesaurus words for "denature":
   accommodate, adapt, adjust, adulterate, alloy, alter, ameliorate,
   bastardize, better, break up, canker, change, cheapen, coarsen,
   confound, contaminate, convert, corrupt, cut, debase, debauch,
   defile, deflower, deform, degenerate, degrade, denaturalize,
   deprave, desecrate, despoil, devalue, dilute, distort, diversify,
   doctor, doctor up, fit, fortify, improve, infect, lace, meliorate,
   misuse, mitigate, modify, modulate, mutate, overthrow, pervert,
   poison, pollute, prostitute, qualify, ravage, ravish, re-create,
   realign, rebuild, reconstruct, redesign, refit, reform, remake,
   renew, reshape, restructure, revamp, revive, ring the changes,
   shift the scene, shuffle the cards, spike, subvert, taint,
   tamper with, turn the scale, turn the tables, turn the tide,
   turn upside down, twist, ulcerate, vary, violate, vitiate,
   vulgarize, warp, water, water down, work a change, worsen