thumbscrew

[ thuhm-skroo ]

/ ˈθʌmˌskru /

a screw, the head of which is so constructed that it may be turned easily with the thumb and a finger.

Often thumbscrews. an old instrument of torture by which one or both thumbs were compressed.

Origin of thumbscrew

First recorded in 1705–15; thumb + screw

A painted target, arranged with a slide to be moved up and down on this staff, and held by a thumbscrew, will be found useful.

Farm drainage |Henry Flagg French
The thumbscrew would extort a confession from a dead man; and the rack—well, that is something inconceivably devilish.

Nasby in Exile |David R. Locke
The small fitting under the gasoline tank has a thumbscrew shutoff and a glass-sight feed tube, leading to the carburetor.

Smithsonian Institution - United States National Museum - Bulletin 240 |Anonymous
The valve should be of the "screw-down" pattern, either with a thumbscrew, wheel and spindle, or a key.

The Turkish Bath |Robert Owen Allsop

The thumbscrew is to be adjusted so that the free end of "F" will rest against it in a temperature of 70 Fahr.

Rules and Practice for Adjusting Watches |Walter J. Kleinlein

thumbscrew

/ (ˈθʌmˌskruː) /

an instrument of torture that pinches or crushes the thumbs

a screw with projections on its head enabling it to be turned by the thumb and forefinger