secret police

police force that works in secret to ensure that citizens behave as their government wants 秘密警察.

second hand, second in command, second lieutenant, second sight, second-best, second-degree, second-guess, second-hand, second-rate, second-string, secondarily, secondary, seconder, secondhand, secondly, secondment, secrecy, secrecy (title), secret, secret agent (also agent), secret service, secretarial, secretariat, secretary, Secretary of State, Secretary-General, secrete, secretion, secretive, secretively, secretiveness, secretly, sect, sectarian, sectarianism, section, sectional, sectionalism, sector, secular,