from The Century Dictionary.
- noun A key for turning a screw. It may be a form of screw-driver, or a form of wrench. See cut under
- noun A socket-wrench in which the socket is formed on the end of the shank to receive the nut or head and the shank is turned by a crosspiece or T-head.
- noun A form of adjustable wrench, or monkey-wrench, in which the movable jaw is held from slipping on the shank by a tapering wedge or key, the latter being adjustable lengthwise by a screw either on the shank or parallel to it.
Sorry, no etymologies found.
He were one too mony, however, for he up wi 'his screw-key and laid mi yed open, an'
Lancashire Idylls (1898) Marshall Mather
A wrest is a special tool used "for turning bolts, nuts, etc.; a screw-key," apparently used in this instance to tighten the saw blade in the frame.