1) a member of a legislative assembly (legislator)
2) the senior part (house) of a two part legislative assembly in some countries, e.g. France, US; the governing council of some universities (senate)
3) a constitutional right of a sovereign, president, legislative assembly or other body, or a member of the United Nations Security Council, to reject of forbid something; statement that rejects or prohibits something (veto)
(in the USSR) an elected council at local, regional or national level forming part of the system of government
federal assembly