Where does “sessitare” come from?

sessitare (Latin) comes from Latin sessum, from Latin sedeō, from Proto-Italic sedēō, from Proto-Indo-European sḗd- — to sit.

Ancestry of “sessitare”, step by step

Step	Language	Word	Meaning
1	Latin	sessum	perfect passive participle of sedeō; accusative...
2	Latin	sedeō	to sit, to be seated
3	Proto-Italic	sedēō	sit, be sitting, be seated
4	Proto-Indo-European	sḗd-	to sit