n.1 a legislative body, esp. the upper and smaller assembly in the US, France, and other countries, in the States of the US, etc.
2 the governing body of a university or (in the US) a college.
3 Rom.Hist. the State council of the republic and empire sharing legislative power with the popular assemblies, administration with the magistrates, and judicial power with the knights.
Etymology: ME f. OF senat f. L senatus f. senex old man