Flōrĭānus, i, m., a Roman surname. Esp., M. Annius, half-brother of the emperor Tacitus, after whose death he usurped the empire, A. D. 276, but after a few weeks met an obscure death at Tarsus, Aur. Vict. Caes. 36, 37; Eutr. 9, 10; v. esp. Vop. Flor.