an act of usurping; wrongful or illegal encroachment, infringement, or seizure.
2.
illegal seizure and occupation of a throne.
Origin: 1350–1400; Middle English < Latin ūsūrpātiōn- (stem of ūsūrpātiō), equivalent to ūsūrpāt(us) (past participle of ūsūrpāre to usurp) + -iōn--ion