Tenterhooks or tenter hooks are hooked nails in a device called a tenter. Tenters were originally large wooden frames which were used as far back as the 14th century in the process of making woollen cloth. After a piece of cloth was woven, it still contained oil and dirt from the fleece. A craftsman called a fuller (also called a tucker or wa[u]lker) cleaned the woollen cloth in a fulling mill, and then had to dry it carefully or the woollen fabric would shrink. To prevent this shrinkage, the ful...