antepenultimate vs antepenult

antepenultimate and antepenult both are nouns.

Word	Noun	Adjective	Verb	Adverb
antepenultimate	Yes	Yes	No	No
antepenult	Yes	No	No	No

As nouns, antepenultimate and antepenult are synonyms defined as:

antepenultimate and antepenult: the 3rd syllable of a word counting back from the end

Other synonyms of antepenultimate include antepenultima.

antepenultimate (noun)	antepenult (noun)
the 3rd syllable of a word counting back from the end	the 3rd syllable of a word counting back from the end

antepenultimate (adjective)	antepenult (adjective)
third from last