OK, hands up who’s actually got these two mixed up? I’m sharing this Troublesome Pair mainly because a) someone suggested it (who? I suspect it might have been Mr. Libro, who is a great source of inspiration for these) and b) isn’t the word formication excellent? There’s a bonus word in the works, too. I’d love to know which word you were looking up when you found this article – do share in the comments!

Fornication is officially the act of having sexual intercourse with someone to whom you are not married. The OED marks this as being “formal or humorous” which seems an amusing and odd pairing to me, but also quite true.

Formication is the sensation of having insects (it comes from the word for ant, also found supplying formic acid, which is emitted by some ants) crawling on your skin. It forms part of some medical conditions (or comes from having insects crawling on your skin).

And I’m always reminded of the word vermiculation by formication – it’s another word from the world of fauna, meaning marking with wavy or wiggly lines or, indeed, worm-eaten (the latter being “archaic” according to the OED. I’ve always come across the first meaning in relation to a particular type of decoration on stone, although if you have a look at this Wikipedia article, you’ll find it’s used in enamel work, too.

Don’t say you never learn anything here!

You can find more troublesome pairs here, and here’s the index to them all!