usurpative

• a word derived from usurp.
  usurp

  verb (used with object)

  to seize and hold (a position, office, power, etc.) by force or without legal right.
• a word derived from usurpation.
  usurpation

  noun

  an act of usurping; wrongful or illegal encroachment, infringement, or seizure.

Related Words

• annex
• preempt
• supplant
• wrest