Thumb"kin (?), n. An instrument of torture for compressing the thumb; a
thumbscrew.
Thumb"less, a. Without a thumb. Darwin.
Thumb"screw` (?), n. 1. A screw having a flat-sided or knurled head, so
that it may be turned by the thumb and forefinger.
2. An old instrument of torture for compressing the thumb by a screw; a
thumbkin.