Methylated spirit

alcohol which has had the methyl group added to it

Denatured alcohol is ethanol which has been rendered toxic or otherwise undrinkable, and in some cases dyed. It is used for purposes such as fuel for spirit burners and camping stoves, and as a solvent. Traditionally, the main additive was 10% methanol, which gave rise to methylated spirits. There are diverse industrial uses for ethanol, and therefore literally hundreds of recipes for denaturing ethanol. Typical additives are methanol, isopropanol, methyl ethyl ketone, methyl isobutyl ketone, denatonium, and even (uncommonly) aviation gasoline.
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Noun
1. ethyl alcohol denatured with methyl alcohol to prevent its use as an alcoholic beverage
(hypernym) denatured alcohol
(hyponym) surgical spirit