abstinent vs abstentious

abstinent is a noun but abstentious is not a noun.

Word	Noun	Adjective	Verb	Adverb
abstinent	Yes	Yes	No	No
abstentious	No	Yes	No	No

As adjectives, abstinent and abstentious are synonyms defined as:

abstinent and abstentious: self-restraining; not indulging an appetite especially for food or drink

abstinent (noun)	abstentious (noun)
a person who refrains from drinking intoxicating beverages

abstinent (adjective)	abstentious (adjective)
self-restraining; not indulging an appetite especially for food or drink	self-restraining; not indulging an appetite especially for food or drink