Merriam-Webster Collegiate Dictionary - usurp

 verb  Etymology: Middle English, from Anglo-French usorper, from Latin ~are to take possession of without legal claim, from usually (ablative of usus use) + rapere to seize — more at rapid  Date: 14th century  transitive verb  1.  a. to seize and hold (as office, place, or powers) in possession by force or without right ~ a throne  b. to take or make use of without right ~ed the rights to her life story  2. to take the place of by or as if by force ; supplant must not let stock responses based on inherited prejudice ~ careful judgment  intransitive verb to seize or exercise authority or possession wrongfully  • ~ation noun  • ~er noun