Mid 17th century (in an earlier sense). From classical Latin potestās power, authority, control, position of power, office, ruler, magistrate, spiritual power, property, healing property, phonetic or phonemic value of a letter in an alphabet, in post-classical Latin also member of an order of angels (Vulgate), demon (Vulgate), angel (3rd cent.), magistrate in medieval Italy, mathematical power from potis having the power, able + -tās, perhaps after maiestās beside magis more.