FOR THE ONCE

In etymology, a nonce formation is a word extemporaneously coined for a specific purpose. In other contexts, the word nonce can refer to an arbitrary number in cryptography or serve as a slang word for "pedophile". The last meaning might be from the unrelated word nancyboy, but the first two definitions come from the still-in-use phrase for the nonce, meaning "for the present". However, around the twelfth century, this was spelled for than ance! This corresponds to "for the once" in modern words, with than being an altered form of the dative declension of the. As that meaning of than got increasingly rarer, people assumed that the spelling was wrong as is and actually had to be the, so the n got moved to the start of the next word in a process linguists call "rebracketing".