Lewis & Short

sēvĭrālis, e, adj. [sevir], of or belonging to a sexvir: ludi, of the equestrian sexvirs, Capitol. M. Aurel. 6: cena, of the Augustan sexvirs.
Hence, subst.: sēvĭrā-les, ium, the Augustan sexvirs: ORDO SEVIRALIVM, Inscr. Orell. 2229; Inscr. Murat. 1104, 7.