noun
the government agency in the United Kingdom that is responsible for internal security and counterintelligence on British territory
• Syn: ↑Security Service, ↑MI
• Regions: ↑United Kingdom, ↑UK, ↑U.K., ↑Britain, ↑United Kingdom of Great Britain and Northern Ireland, ↑Great Britain
• Hypernyms: ↑international intelligence agency
Useful english dictionary. 2012.