Killer

I expect a philologist....

Let's start with "philology". It's a term that isn't much used any more, but it used to mean "comparative linguistics"; it's from the Greek words for "love of learning". I first ran across the term in a Eugene Ionesco play, "The Lesson", about which you can read much more here. I do not think philology necessarily leads to murder, but you never know.

Now then. I expect a philologist would have no problem looking at most words and figuring out where they might have come from, being a professional and all, but schlubs like me, with their lack of a Ph.D. and their day jobs and their blogs and whatnot, have to make (more or less) educated guesses.

I don't know why the word "atrocious" popped up, but I was determined to get as far as I could in figuring out without the use of a dictionary where it might have come from. I didn't get very far.

The whole thing suggested Latin, but then the first syllable might be a negation, as it so often is in Latinate English words, and I couldn't imagine what the rest of the word was that was being negated. I decided that it wasn't that, but after that point I was pretty much stuck.

And with good reason! It was from an Indo-European root which I'd never heard before and which left hardly any English relatives. There was nothing for me to compare the word to.

The root in question is "ater-", which means, unexpectedly, "fire". There are three common English words from this stem, and you will never guess any of them, except "atrocious", which I've already given you. It's from Latin (at least I got that part right) "atrox", "frightful"; that itself is compounded from two IE stems, "ater-", "fire" and "-okw-", "to look. The meaning of the "ater-" stem is debatable: the whole thing might mean "having a fiery (and therefore threatening) countenance", but the word "ater" in Latin meant "blackened by fire" and so the whole word could mean "having a black (fierce, forbidding) countenance".

The "blackened by fire" sense comes up in the second of the "ater-" words, "atrium". Nowadays it's a wide-open central court, but in Roman days, it was the forecourt, and the name seems to come from the hearth situated in it; a hole in the ceiling would allow smoke to escape.

The third "ater-" word in English is "zircon". Yeah, I know, you'd never think it to look at it. Old Persian "atar", "fire", became "adur" in Middle Persian, then "azar" in Persian. Then it was "azargun", "the colour of fire", and then Greek "surikon", Arabic "sirigun", and finally German "Zirkon".