Where does “selcouth” come from?

selcouth (Middle English) comes from Old English selcūþ, from Old English seld-, from Old English seld, from Old English setl, from Proto-Germanic setlaz, from Proto-Indo-European sḗd- — to sit.

Ancestry of “selcouth”, step by step

Step	Language	Word	Meaning
1	Old English	selcūþ	—
2	Old English	seld-	rare, infrequent; unusual; special
3	Old English	seld	—
4	Old English	setl	sitting, residence; seat, bench, throne; setting
5	Proto-Germanic	setlaz	seat; chair; settle
6	Proto-Indo-European	sḗd-	to sit

Words derived from “selcouth”

selcouth
selcouthly

Every word from Proto-Indo-European sḗd- →Every word from Proto-Germanic setlaz →Every word from Old English setl →