Specificity

From the wonderfully multifaceted blog Pharyngula, which is nominally about biological science but covers a whole lot of ground:

For example, and this is a very small thing that will grate on any biologist, is that he refers to single species as "specie". The singular of species is "species"; specie is money in the form of coins. The third time Fleury did this, it was driving me nuts.

It isn't just biologists that it grates on, of course. It isn't a mistake that I see often, but it drives me nuts, too.

There are some words in English that look like plurals but aren't (necessarily), and can't be converted into the singular form by removing the final letter. "Species" is one. So are "kudos", "pathos", and "bathos", not to mention "mathematics", "congeries", and "measles".

"Specie", meaning "money in the form of coins (as opposed to banknotes and bullion)", is, you will surely have guessed, related to "species", which I wrote about eons ago and will therefore not bother to recapitulate.