Is it 'nerve-racking' or 'nerve-wracking'?

If you've ever paused mid-sentence, finger hovering over the keyboard, unsure whether to write nerve-racking or nerve-wracking, you are in good company. The good news is that the two have coexisted peacefully for long enough that we've pretty much decided that both are correct.

The case for nerve-racking is largely a historical one. Rack traces back to the Old English reccan, meaning "to stretch," and is the same word behind the medieval torture device that stretched its victims on a wooden frame. To rack someone's nerves, then, is to stretch them to their limit; a vivid, if unpleasant, image. We enter nerve-racking as an adjective meaning "extremely trying on the nerves," and treat nerve-wracking as a variant spelling. Nerve-racking is the older of the two, in use since the beginning of the 19th century.

The happy hit produced a positive babel of uproarious applause, and we question whether the fair creatures who were the occasion of it, were proof against such nerve-racking shouts.
— North Wales Chronicle, 8 Mar. 1836

Wrack, on the other hand, comes words associated with vengeance, persecution, and misery (the Old English wracu and wræc). It is closely related to wreck, and carries with it a feeling of total destruction rather than mere stretching. One could argue that nerve-wracking is actually the more dramatically expressive of the two: your nerves aren't just being strained, they're being wrecked. On the other hand, it is decidedly an offshoot of nerve-racking, and didn’t appear in print until the end of the 19th century.

The newer version (nerve-wracking) has become the more commonly used spelling in modern English; a pattern familiar to anyone who has watched language drift away from its etymological moorings and toward whatever feels most natural to the ear. This sort of drift is not surprising. Rack and wrack are pronounced identically, and their meanings have considerable overlap in modern usage. It's not hard to see how a writer might think of the word wrack (the one associated with ruin, as in wrack and ruin), decide to pair it with nerve, and stay there because no one corrected them. Over time, enough writers made the same "error" that it stopped being an error at all.

Some traditionalists favor nerve-racking, pointing to its longer documented history and its more logical etymological connection. But the descriptive reality is that both spellings appear regularly in edited prose, and neither will get you in serious trouble. The one thing you can say with confidence is that whichever form you choose, the experience it describes (the damp palms, the tight chest, the sense that time is moving both too fast and too slowly) is spelled exactly right.