Where does “dimethyl” come from?

Dimethyl comes from English di- and methyl, where methyl derives from Ancient Greek διά and μέθυ, ultimately from Proto-Indo-European dwís and dwóh₁.

dimethyl (English): Two methyl groups in a molecule

Definitions

Step	Language	Word	Meaning
1	English	di-	API; two, twice, or double; Alternative form of...
2	Latin	dī-	—
3	Ancient Greek	δί-	—
4	Ancient Greek	διά	throughout
5	Proto-Indo-European	dwís	twice, doubly; in two
6	Proto-Indo-European	dwóh₁	two

dimethyl — Etymology, Origin & Word History | Etymology Explorer