usurpation vs usurp

usurpation is a noun but usurp is not a noun.

Word	Noun	Adjective	Verb	Adverb
usurpation	Yes	No	No	No
usurp	No	No	Yes	No

usurpation (noun)	usurp (noun)
wrongfully seizing and holding (an office or powers) by force (especially the seizure of a throne or supreme authority)
entry to another's property without right or permission

usurpation (verb)	usurp (verb)
	seize and take control without authority and possibly with force; take as one's right or possession
	take the place of