deputy

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

• noun A person appointed or empowered to act for another.
• noun An assistant exercising full authority in the absence of his or her superior and equal authority in emergencies.
• noun A representative in a legislative body in certain countries.

from The Century Dictionary.

• noun A person appointed or elected to act for another or others; one who exercises an office in another's right; a lieutenant or substitute.
• noun Specifically
• noun One deputed to represent a body of electors; one elected to the office of representative: as, the deputies to the French Chamber of Deputies.
• noun In law, one who by authority exercises another's office or some function thereof, in the name or place of the principal, but has no interest in the office.
• Serving as a deputy; deputed: as, a deputy sheriff.

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

• noun One appointed as the substitute of another, and empowered to act for him, in his name or his behalf; a substitute in office; a lieutenant; a representative; a delegate; a vicegerent
• noun France A member of the Chamber of Deputies.
• noun one of the two branches of the French legislative assembly; -- formerly called Corps Législatif. Its members, called deputies, are elected by the people voting in districts.

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

• noun One appointed as the substitute of another, and empowered to act for him, in his name or his behalf; a substitute in office; a lieutenant; a representative; a delegate; a vicegerent; as, the deputy of a prince, of a sheriff, of a township, etc.
• noun : A member of the Chamber of Deputies, formerly called Corps Législatif
• noun Ireland a member of Dáil Éireann, or the title of a member of Dáil Éireann. (Normally capitalised in both cases)

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

• noun a member of the lower chamber of a legislative assembly (such as in France)
• noun a person appointed to represent or act on behalf of others
• noun an assistant with power to act when his superior is absent
• noun someone authorized to exercise the powers of sheriff in emergencies