Where does “dul” come from?

dul (Middle English) comes from Old English dol, from Proto-West Germanic *dol, from Proto-Germanic dulaz, from Proto-Germanic dwalaz, from Proto-Indo-European dʰwel-.

Ancestry of “dul”, step by step

Step	Language	Word	Meaning
1	Old English	dol	foolish
2	Proto-West Germanic	*dol	—
3	Proto-Germanic	dulaz	confused, stunned; foolish, misled, mad
4	Proto-Germanic	dwalaz	confused, stunned; foolish, misled, mad
5	Proto-Indo-European	dʰwel-	—

Words derived from “dul”

dull
dullness
dully
duller
doldrums
dolt
doltish
dullish
doldrum
dold
dulleth
doltishness
doltishly
dullhead
dullwittedness
dullen
dullishly
dullwit
dull-headed
dolthood
dullsome
dull-witted
dollen
dullen

Every word from Proto-Indo-European dʰwel- →

dul — Etymology, Origin & Word History | Etymology Explorer