denaturation

of alcohol
https://doi.org/10.1351/goldbook.D01587
Addition of methanol or acetone to alcohol to make it unfit for drinking.
Source:
PAC, 1993, 65, 2003. 'Glossary for chemists of terms used in toxicology (IUPAC Recommendations 1993)' on page 2036 (https://doi.org/10.1351/pac199365092003)