senate

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An assembly or a council of citizens having the highest deliberative and legislative functions in a government, specifically.
• noun The upper house of the US Congress, to which two members are elected from each state by popular vote for a six-year term.
• noun The upper house in the bicameral legislature of many states in the United States.
• noun The upper legislative house in Canada, France, and some other countries.
• noun The supreme council of state of the ancient Roman Republic and later of the Roman Empire.
• noun The building or hall in which such a council or assembly meets.
• noun A governing, advisory, or disciplinary body of some colleges and universities composed of faculty members and sometimes student representatives.

from The Century Dictionary.

• noun An assembly or council of citizens invested with a share in the government of a state.
• noun In an extended use. a body of venerable or distinguished persons.
• noun The governing body of the University of Cambridge, and of some other institutions of learning.
• noun In certain American colleges, where the students take part in the discipline of the institution, a disciplining and advisory body composed of members of the faculty and representatives of the students.

from the GNU version of the Collaborative International Dictionary of English.

• noun An assembly or council having the highest deliberative and legislative functions.
• noun (Anc. Rom.) A body of elders appointed or elected from among the nobles of the nation, and having supreme legislative authority.
• noun The upper and less numerous branch of a legislature in various countries, as in France, in the United States, in most of the separate States of the United States, and in some Swiss cantons.
• noun In general, a legislative body; a state council; the legislative department of government.
• noun engraving The governing body of the Universities of Cambridge and London.
• noun United States In some American colleges, a council of elected students, presided over by the president of the college, to which are referred cases of discipline and matters of general concern affecting the students.
• noun a room where a senate meets when it transacts business.
• noun a house where a senate meets when it transacts business.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun In some bicameral legislative systems, the upper house or chamber.
• noun A group of experienced, respected, wise individuals serving as decision makers or advisors in a political system or in institutional governance, as in a university, and traditionally of advanced age and male.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the upper house of the United States Congress
• noun assembly possessing high legislative powers