secret police

WordReference Random House Unabridged Dictionary of American English © 2026

se′cret police′, 

1. Government a police force that functions as the enforcement arm of a government's political policies and whose activities, which often include surveillance, intimidation, and physical violence as a means of suppressing dissent, are usually concealed from the public. Also called security police. 

• 1920–25

Collins Concise English Dictionary © HarperCollins Publishers::

secret police noun

1. a police force that operates relatively secretly to check subversion or political dissent