major premise vs major premiss

major premise and major premiss both are nouns.

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

As nouns, major premise and major premiss are synonyms defined as:

major premise and major premiss: the premise of a syllogism that contains the major term (which is the predicate of the conclusion)

major premise (noun)	major premiss (noun)
the premise of a syllogism that contains the major term (which is the predicate of the conclusion)	the premise of a syllogism that contains the major term (which is the predicate of the conclusion)