thumbscrew
thumb.screw \'th*m-.skru:\ n 1: a screw having a flat-sided or knurled head so that it may be turned by the thumb and forefinger 2: an instrument of torture for compressing the thumb by a screw
thumb.screw \'th*m-.skru:\ n 1: a screw having a flat-sided or knurled head so that it may be turned by the thumb and forefinger 2: an instrument of torture for compressing the thumb by a screw