millenarism vs millenniumism

millenarism and millenniumism both are nouns.

Word	Noun	Adjective	Verb	Adverb
millenarism	Yes	No	No	No
millenniumism	Yes	No	No	No

As nouns, millenarism and millenniumism are synonyms defined as:

millenarism and millenniumism: belief in the Christian doctrine of the millennium mentioned in the Book of Revelations

Other synonyms of millenarism include chiliasm, millenarianism.

millenarism (noun)	millenniumism (noun)
belief in the Christian doctrine of the millennium mentioned in the Book of Revelations	belief in the Christian doctrine of the millennium mentioned in the Book of Revelations