Origin: Latin suffix -ate
Penultimate has 5 different meanings across 2 categories:
the next to last syllable in a word
A penult, a next to last
The penultimate day of a month.
second last
"the author inadvertently reveals the murderer in the penultimate chapter"
"the figures in the next-to-last column"
Next to last, second to last; immediately preceding the end of a sequence, list, etc.
The word comes from the Latin paenultimus, which combines paene meaning "almost" and ultimus meaning "last." It originally described something that is second to last.