penult

[pee-nuhlt, pi-nuhlt] /ˈpi nʌlt, pɪˈnʌlt/
noun
1.
the next to the last syllable in a word.
Also, penultima
[pi-nuhl-tuh-muh] /pɪˈnʌl tə mə/ (Show IPA)
.
Origin
1530-40; < Latin paenultima (syllaba), contraction of paene ultima almost the last; see pen-, ultima
British Dictionary definitions for penult

penult

/ˈpɛnʌlt; pɪˈnʌlt/
noun
1.
the last syllable but one in a word
Word Origin
C16: Latin paenultima syllaba, from paene ultima almost the last
Word Origin and History for penult
adj.

"last but one," 1530s, abbreviation of penultima. As a noun from 1570s.