Slang definitions & phrases for under someone's thumb
under someone's thumb
Entirely in someone's control: Our boss likes to keep us under his thumb(1754+)
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with under someone's thumb
Controlled or dominated by someone, as in He's been under his mother's thumb for years. The allusion in this metaphoric idiom is unclear, that is, why a thumb rather than a fist or some other anatomic part should symbolize control.