Purge from your mind the idea that this word may refer to a heretical sibling. Oh, the history of the Cathars is one rooted in catharsis, to be sure: they saw themselves as purged of sin, and so more pure, and they in turn were purged from the church – no one likes a holier-than-thou, and no one likes them less than other holier-than-thous. That engenders a transactional mismatch, each party playing the parent role to the other. But catharsis refers more often in modern English to a purging of the emotions, a release more in line with Freudian theory than with transactional analysis. It can also be used in reference to Aristotelian aesthetic theory, in an interesting contrast: whereas in psychotherapy the catharsis is accomplished by reconnecting the errant emotional reaction to its original impetus, in Aristotle it’s accomplished instead by reacting to a fictional surrogate, a sort of inoculation. And if you think that that is all, er, crap, well, that leads us to the physical sense, of which no more need be spoken here.
But is this word so purgative in its phonaesthetics? The experience of saying it is reminiscent perhaps of spitting a watermelon seed, or rather trying once to spit it and then having to hiss a remaining bit off the tip of the tongue. But all those soft sounds seem so pure, like an alabaster statue of, well, someone named Catherine, perhaps. And fair enough: although the ultimate source of Catherine is Aikateriné, the name of an early Hellenic saint, its form has long been influenced by katharos, Greek for “pure” and the ultimate source of our word du jour. And although catholic and cathedral also have different sources, we can see something so ecclesiastically white and pure in the overtones of cath that even cathode ray tube may seem softened by it. Certainly it sounds so much smoother and nicer than purgation, with that urg in there all too iconic. And the is at the end keeps it classically Greek, all white and pure. Except that the classical Greeks actually painted their temples and statues; they’re white now just because paint comes off. Does that seem like heretical revision? In this case – as in many others, notably including some prescriptivist notions in English – the “return to purity” is the real revision, an imposition to be shed like so many cat’s hairs.