I was listening to Radiohead this afternoon, specifically their most recent album, A Moon Shaped Pool (it’s pretty good).

I’d noticed, as I often have before, the pun in the lyrics of the song “Decks Dark:” in split infinity. A play, of course, on split infinitive, but it made a question come to my mind that had never occurred to me before: what’s the link between the words infinity and infinitive?

There must be a direct etymological link, but there was no obvious link, for me, between an uninflected form of a verb, and the concept of space without limits.

At least infinite on its own is pretty transparent. Just by looking at it, it clearly means without end. And yet, while the word infinitive is also clearly derived from the Latin infinitus (not limited), I couldn’t for the life of me imagine the link.

So I did a little digging, and the Late Latin word infinitivus helps to clear things up a bit. It’s from this word, itself derived from infinitus, that infinitive is more directly derived. It could mean infinite, or indefinite. Infinitive is derived more from the indefinite meaning, as an infinitive form of a verb is not defined or restricted by person or number.

And that’s now not so far from the concept of infinity, as like the eternal void of the universe, there are no limits placed on an infinitive form of a verb. Though it’s still not infinite of course, but if you’re of a romantic bent, you might think of an infinitive verb as a source of infinite possibilities, that we only limit to a certain range when we open our mouths and attach an -s or an -ed to the verb.