Where does “dimm” come from?

dimm (Old English) comes from Proto-Germanic dimmaz, from Proto-Indo-European dʰem- — to whisk, smoke, blow; dust, haze, cloud; obscure.

dimm (Old English): dim

Definitions

Step	Language	Word	Meaning
1	Proto-Germanic	dimmaz	dark; gloomy
2	Proto-Indo-European	dʰem-	to whisk, smoke, blow; dust, haze, cloud; obscure

dimm — Etymology, Origin & Word History | Etymology Explorer