Refers to rulers who exercise absolute, unrestricted power over the government of a nation or state. It often refers to non-hereditary rulers. The term may also be used in its original sense, which was as the title of officials of ancient Rome and later Italian states who were elected in times of crisis and invested with absolute authority for the duration of the emergency. For rulers who exercise their power cruelly, oppressively, or unjustly, see "tyrants.".