Where does “сена́т” come from?

сена́т (Russian) comes from Latin senātus, from Latin -ātus, from Proto-Italic -ātos, from Proto-Indo-European -éh₂tos.

сена́т (Russian): senate

Definitions

Step	Language	Word	Meaning
1	Latin	senātus	—
2	Latin	-ātus	—
3	Proto-Italic	-ātos	—
4	Proto-Indo-European	-éh₂tos	—

сена́т — Etymology, Origin & Word History | Etymology Explorer