Where does “arco” come from?

arco (English) comes from Italian arco, from Latin arcus, from Latin solium, from Proto-Indo-European sodyom, from Proto-Indo-European sḗd- — to sit.

arco (English): A note in string instrument musical notation...

Definitions

Step	Language	Word	Meaning
1	Italian	arco	bow; arc; arch
2	Latin	arcus	arc, arch; bow; rainbow
3	Latin	solium	seat, chair; throne, chair of state, official...
4	Proto-Indo-European	sodyom	—
5	Proto-Indo-European	sḗd-	to sit