/ juːˈzɜːp; NAmE -ˈzɜːrp/ verb
[ vn ] ( formal ) to take sb's position and/or power without having the right to do this
► usurp·ation / ˌjuːzɜːˈpeɪʃn; NAmE -zɜːrˈp-/ noun [ U , C ]
► usurp·er noun
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WORD ORIGIN
Middle English (in the sense appropriate a right wrongfully) : from Old French usurper , from Latin usurpare seize for use.