Coffee and tea

Le porte-filtre is not a noun with something stuck in front of it: it is a small sentence. French names a great many tools by putting a verb first and its object second, so the object is described by what it does. The thing that carries the filter, the thing that carries the coins, the thing that carries the keys: un porte-monnaie, un porte-clés, un porte-parole, un porte-bagages and, at sea, un porte-avions. Two consequences follow, and both matter before writing one down. The first half is a verb form and never varies, so nothing is ever added to porte- however many there are. Whatever does change falls on the noun behind it: des porte-filtres. And where that noun is already plural in the singular, as in un porte-clés, nothing changes at all. English builds the same objects the other way round, with the noun last: « filter holder », « key ring », « luggage rack ». For this one machine it skipped its own pattern and took the word ready-made from Italian, which is why a barista says « portafilter » and not « filter holder ».