An unpleasant, disharmonious noise is called “cacophony”. Although that’s the only word in its family that most people are familiar with, there exists a whole family of English words that (1) mean something unpleasant, and (2) begin with “cac-“. The prefix is pretty straightforward; it comes from the Greek word “kakos” (bad).
Most, but not all of the words in this family are obsolete terms that used to be used in the medical field. “Cacothymia”, for instance, is a confused or disordered mental condition, and “caconychia” is a disease of the fingernails or toenails. But there are also some family members, like “cacophony”, that are (or were) common terms. “Cacography” is bad handwriting — although now that I think of it, maybe that one IS a medical term; the handwriting of doctors is famously cacographic.
There’s even a blanket term for anybody in a bad mood with an overwhelming urge to do something bad: “cacoethes”. This can be something minor — you can blame cacoethes for finishing a second slice of cake — or something more like a temper tantrum where china plates are flung at walls. There also used to be a well-known phrase suggesting that a piece of writing really shouldn’t have been attempted in the first place: “cacoethes scribendi.” It more literally means that someone (unfortunately) suffered from the inescapable urge to write, which they did badly. It was a common enough phrase to be included in a dictionary of quotations in 1808, and it actually comes from a longer quotation by the Roman author Juvenal: “Tenet insanabile multos scribendi cacoethes.” That means “many suffer from the incurable disease of writing.” It probably stayed stuck in its original Latin because after all, if you’re going to sneer at somebody else’s writing, saying so in Latin makes your personal superiority much more obvious. At least it did back in the 18th century.
That 1808 dictionary of quotations (written by D. E. Macdonnel) includes a couple of others from the cacoethes family. These could also be usefully revived, since the behaviors they describe are certainly still with us. “Cacoethes loquendi” is the uncontrollable urge to say something (“loquendi” comes from “loqui”, the Latin word for “speak” — it’s also the source of “loquacious”). And “cacoethes carpendi” is the compulsion to collect things. “Carpendi” comes from “carpere”, the Latin word for pick or choose. The “picking” aspect of “cacoethes carpendi” gave the phrase another meaning as well: the overwhelming urge to criticize. It was fault-finding that was inherently worse than mere criticism, though. After all, “criticism” comes from the Greek “kritikos”, which means skilled in judging. Cacoethes carpendi, in comparison, is just a cacophony of carping.
