Penultimate is an adjective that describes something or someone as almost the final in a set or series, more specifically the one right before the last one.
The adverb form is penultimately. This version is uncommon, though it is logical and necessary in some instances. An even more rare, and questionable, form is the noun form of penultimateness. This form should be avoided in formal writing.
The noun form is penult, which is more specifically used for the second-to-last syllable in a word. A variation of penult is penultima and has the exact same meaning. It should be noted that both of these words are uncommon and in general seen to be arcane versions of penultimate.
Examples
Spoiler reports for the penultimate episode of the hit medical TV drama series “Grey’s Anatomy” Season 11 titled “Time Stops” hinted more unfortunate events to come. [Christian Post]
I wondered if this penultimately scheduled home game could turn out to be Jeter’s last. [CBS Local New York]
Then it’s back to business, and we are struck with the penultimateness of it all. [The Washington Post]
EC played out his 1986 identity crisis in the media, conducting “The Elvis Costello Show” as Declan Patrick Aloysius MacManus (all but the penult are his actual given names) and leaving his band, the Attractions, to record the brilliant but somewhat strained and abashed The King of America with Jerry Scheff and James Burton of that other Elvis’s band. [Stereophile]
The German duo of Marcus Burghardt and John Degenkolb led up the climb of Via Salviati for the penultima time, after the two leaders had been swept up. [Road Cycling UK]