Where does “nondimmable” come from?

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

Ancestry of “nondimmable”, step by step

nondimmable traces back through two separate lines of ancestry.

via English dimmable

Step	Language	Word	Meaning
1	English	dimmable	Able to be dimmed; able to have illumination...
2	English	Dim	(from Bashkir Дим)
3	Middle English	dim	—
4	Old English	dim	—
5	Old English	dimm	dim
6	Proto-Germanic	dimmaz	dark; gloomy
7	Proto-Indo-European	dʰem-	to whisk, smoke, blow; dust, haze, cloud; obscure

via English non

Step	Language	Word	Meaning
1	English	non	Obsolete form of none
2	French	non	no; not; a no, a negative response
3	Old French	non	no; not; Alternative form of nom
4	Latin	nōn	not
5	Old Latin	noenum	—
6	Proto-Indo-European	óynos	one; single

Every word from Proto-Indo-European dʰem- →Every word from Proto-Germanic dimmaz →Every word from Old English dimm →