To take away a natural characteristic or inherent property of (a thing or a person).
To add something to (alcohol) that makes it unsuitable for consumption but leaves it suitable for other purposes.
While you cannot drink denatured alcohol, you can still use it to remove sticker glue from most surfaces.
To alter its original form or state, especially of a protein, by heat, acidity etc.
To combine fissionable material with nonfissionable material in order to prevent its use in an atomic weapon.
Having been deprived of its nature, having had its nature changed.
Of alcohol made undrinkable, by adding a toxin or unpalatable substance, but still useful as a fuel or solvent. Traditionally by the addition of methanol (wood alcohol) to ethanol (grain alcohol).