Q From Lee Becker: What’s the meaning and origin of on tenterhooks?
A It’s been so long since anyone has seen either a tenter, or the hooks on one, that the word and the idea behind it are now quite mysterious, so much so that it sometimes appears as on tenderhooks, which sounds as though it ought to make more sense. But at one time, the phrase on tenterhooks would have evoked an image that was immediately understandable.
It comes from one of the processes of making woollen cloth. After it had been woven, the cloth still contained oil from the fleece, mixed with dirt. It was cleaned in a fulling mill, but then it had to be dried carefully or it would shrink and crease. So the lengths of wet cloth were stretched on wooden frames, and left out in the open for some time. This allowed them to dry and straightened their weave. These frames were the tenters, and the tenter hooks were the metal hooks used to fix the cloth to the frame. At one time, it would have been common in manufacturing areas to see fields full of these frames (older English maps sometimes marked an area as a tenter-field). So it was not a huge leap of the imagination to think of somebody on tenterhooks as being in an state of anxious suspense, stretched like the cloth on the tenter. The tenters have gone, but the meaning has survived.
Tenter comes from the Latin tendere, to stretch, via a French intermediate. The word has been in the language since the fourteenth century, and on tenters soon after became a phrase meaning painful anxiety. The exact phrase on tenterhooks seems first to have been used by Tobias Smollett in Roderick Random in 1748.