“Again” is a word that comes up…well, again and again in conversation. It’s been around for a very long time; at least since Old English. But its meaning contains a surprising little twist.
What you probably think of when you use “again” is repetition; you did something once, and if you do the same thing over, you’re doing it “again.” But think about how that really works. To do something “again” you go back to the beginning. Focus on that word “back” — you’d be returning to the start, going “against” the normal flow of progression. And sure enough, “against,” which can mean being in opposition, is a form of “again.”
Another form is something that used to be a common prefix when you wanted to form a word that meant an opposite. You still see “gainsay” here and there (it’s right on the edge of obsolescence), and to “gainsay” means to speak against or negate. Some of the other old “gain-“ words were “gainrace” (to work against), “gainclap” (to hit back), “gainbuy,” and “gaintake,” which are ways to recover something by buying it back or taking it.
The “reversal” sense that’s always there in “again”, but not always noticed, turns out to be the original sense of “again.” There are examples going back to Old English, but one of the earliest ones that’s still (mostly) readable today is from 1480: “The walshmen..were so stronge that they driuen the englishmen ayene [again].” One of the other aspects of “again” is that over the centuries it’s had a mind-boggling number of spellings, from “ongaegn” to “ageynn” to “ughin,” and about a hundred others.
Regardless of how it’s spelled, though, doing something “again” means repeating it — but used to mean negating it. And “again” might eventually mean that again, which would be sort of against the way we use “again,” but would return “again” back to its roots. Again.