major premise vs premiss

major premise and premiss both are nouns.

Word	Noun	Adjective	Verb	Adverb
major premise	Yes	No	No	No
premiss	Yes	No	Yes	No

As nouns, premiss is a hypernym of major premise; that is, premiss is a word with a broader meaning than major premise:

major premise: the premise of a syllogism that contains the major term (which is the predicate of the conclusion)
premiss: a statement that is assumed to be true and from which a conclusion can be drawn

Other hypernyms of major premise include assumption, premise.

major premise (noun)	premiss (noun)
the premise of a syllogism that contains the major term (which is the predicate of the conclusion)	a statement that is assumed to be true and from which a conclusion can be drawn

major premise (verb)	premiss (verb)
	take something as preexisting and given