Tenterhooks or tenter hooks are hooked nails in a device called a tenter. Tenters were wooden frames which were used as far back as the 14th century in the process of making woollen cloth. The phrase "on tenterhooks" has become a metaphor for nervous anticipation.

What does the expression on tenterhooks mean?

Tenterhooks were used in the process of making woollen cloth. ... The saying 'to be on tenterhooks' originated from this method of controlled drying, used to mean being in a state of uneasiness, anxiety, or suspense.

Is the saying tenterhooks or Tenderhooks?

On tenterhooks NOT on tender hooks

This phrase, meaning worried anticipation, comes from the word 'tenter' which was a frame on which cloth was stretched to prevent shrinking. The tenterhook kept the cloth tense and tight – hence the expression. A tender hook isn't a thing.