Ultimate showed up in the mid seventeenth century, coming from the Late Latin ultimatus and its verb form ultimare. Before that it’s from the classical Latin ultimus, last, which is related to ultra, more. You might not believe this, but that word happens to be the origin word for ultra. I know. It’s pretty tough to believe.
I know you can’t see it, but I’m rolling my eyes.
We can go even further with ultra, all the way back to the Proto Indo European ol-tero-. The ol- gives us the beyond part as it comes from al-, which has given us words like alias and else. Yeah. Ultimate is (distantly) related to else and alias. Who knew?
Of course, there are a few other ultimate words in English. Did you know there used to be a “yesterday” for months? It was the word ultimo, coming from the Latin phrase ultimo menses, or last month. It was in use from the sixteenth to nineteenth centuries and then…I guess we got bored of it? That happens sometimes. There’s also penultimate, which comes from penultima, a word that showed up in the late sixteenth century and means the next to last syllable in a word. It’s from another Latin phrase, penultima syllaba, literally penultimate syllable. The ultima comes from ultimate, while the pen is from paene, almost. Penultimate is…almost last.