An official person who carries out the capital punishment of a criminal. / (archaic) Executor. / A hit man, especially being in some organization.

plural of executioner

(historical) A 16th-century political movement in the Kingdom of Poland and, later, the Polish-Lithuanian Commonwealth, seeking the revendication of public and state lands which were illegally held by various magnates.

(idiomatic) Someone with the roles of judge, jury and executioner; someone with full power to judge and punish others unilaterally.

plural of judge, jury and executioner

(rare) A female executioner.