D defs.my
Entry 1 sense Webster, 1913

Usurper

· U·surp·er · IPA /juˈsɜɹ.pəɹ/
01 n. One who usurps; especially, one who seizes illegally on sovereign power; as, the usurper of a throne, of power, or of the rights of a patron.
  1. 1.
    One who usurps; especially, one who seizes illegally on sovereign power; as, the usurper of a throne, of power, or of the rights of a patron.
    “A crown will not want pretenders to claim it, not usurpers, if their power serves them, to possess it.” South.