Meths is a term commonly used to describe methylated spirits, which is a type of alcohol-based solvent. It is often used as a fuel for portable stoves and for cleaning purposes. However, when it comes to antonyms for this word, the options are limited as there is not an exact opposite word for meths. One can use words like water, soap, or other non-alcoholic solvents to describe alternatives to meths. These substances do not have the same chemical properties or uses as meths, but they serve as safe and effective alternatives for various purposes.