fissiparous vs separatist

fissiparous is not a noun while separatist is a noun.

Word	Noun	Adjective	Verb	Adverb
fissiparous	No	Yes	No	No
separatist	Yes	Yes	No	No

As adjectives, fissiparous and separatist are synonyms defined as:

fissiparous and separatist: having separated or advocating separation from another entity or policy or attitude

Other synonyms of fissiparous include breakaway.

fissiparous (noun)	separatist (noun)
	an advocate of secession or separation from a larger group (such as an established church or a national union)

fissiparous (adjective)	separatist (adjective)
reproducing by fission	having separated or advocating separation from another entity or policy or attitude
having separated or advocating separation from another entity or policy or attitude