Decemvir \De*cem"vir\, n.; pl. E. {Decemvirs}, L. {Decemviri}. [L., fr. decem ten + vir a man.] 1. One of a body of ten magistrates in ancient Rome. Note: The title of decemvirs was given to various bodies of Roman magistrates. The most celebrated decemvirs framed ``the laws of the Twelve Tables,'' about 450 B. C., and had absolute authority for three years. 2. A member of any body of ten men in authority.