Bible Dictionaries
Thumbscrew

Webster's Dictionary

(1):

(n.) An old instrument of torture for compressing the thumb by a screw; a thumbkin.

(2):

(n.) A screw having a flat-sided or knurled head, so that it may be turned by the thumb and forefinger.

Bibliography Information
Webster, Noah. Entry for 'Thumbscrew'. Noah Webster's American Dictionary. https://www.studylight.org/​dictionaries/​eng/​web/​t/thumbscrew.html. 1828.