I'm trying to find out the grammatical name (and origins) of a form of word construction in English (archaic I think). It's when you have a thing, that performs an action on another thing, but those elements are put together the wrong way round to form the actual word. So something that scares crows isn't a crow scarer (as it would be now) but a scarecrow. Something that wards (protects) your robes isn't a robe warder, but a wardrobe. There are probably other examples, though they seem to be a minority, presumably following an archaic pattern that's no longer used. (Otherwise a "dishwasher" would be a "washdish", a "hairdresser" would be a "dresshair", and a "fire fighter" would be a "fightfire".)

I think those kinds of words have a nice ring to them though - I noticed GRRM's mercenaries in Game of Thrones are "Sellswords" instead of "sword sellers", so he seems to have picked up on that too. Any idea where these words come from, and how they're referred to?