means the upper chamber of a legislature, typically smaller and more deliberative than the lower house, whose members debate, revise, and approve laws.

from From Latin senatus, 'a council of elders,' built on senex, 'old man' — the same root that gives us 'senile' and 'senior.' The Romans literally meant a gathering of grey-haired men whose age was supposed to guarantee wisdom; the word traveled into English through Old French senat. So 'senate' has always promised the steadiness of elders — whether it delivers is another matter.