Where does “сенатский” come from?

сенатский (Russian) comes from Russian сена́т, from Latin senātus, from Latin -ātus, from Proto-Italic -ātos, from Proto-Indo-European -éh₂tos — Forms adjectives from nouns, indicating the possession of a thing or a quality.

сенатский (Russian): senate, senatorial

Definitions

senate, senatorial

Ancestry of “сенатский”, step by step

Step	Language	Word	Meaning
1	Russian	сена́т	senate
2	Latin	senātus	—
3	Latin	-ātus	ed
4	Proto-Italic	-ātos	—
5	Proto-Indo-European	-éh₂tos	Forms adjectives from nouns, indicating the possession of a thing or a quality

Every word from Proto-Indo-European -éh₂tos →Every word from Latin -ātus →Every word from Latin senātus →