Where does “сѣдъ” come from?

сѣдъ (Old East Slavic) comes from Proto-Slavic śědъ, from Proto-Slavic xoidъ.

Ancestry of “сѣдъ”, step by step

Step	Language	Word	Meaning
1	Proto-Slavic	śědъ	gray
2	Proto-Slavic	xoidъ	—

Words derived from “сѣдъ”

седой

Every word from Proto-Slavic xoidъ →Every word from Proto-Slavic śědъ →