imperium, regnum, tyrannidem occupare

Etymology:

• tyrannus, tyrannis, tyrannicus are rarely used in the Greek sense, irresponsible sovereign, etc., but usually mean despot, despotic, etc. The pure Latin equivalents are rex, dominus, dominatio, imperium, regius, or if there is emphasis on the cruelty of despots, dominus saevus, crudelis et superba dominatio, etc.