MI5

American

[em-ahy-fahyv] / ˈɛmˌaɪˈfaɪv /

noun

the government's security and counterespionage service that works in liaison with Scotland Yard's Special Branch.

MI5 British

abbreviation

Military Intelligence, section five; a former official and present-day popular name for the counterintelligence agency of the British Government

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of MI5

M(ilitary) I(ntelligence, Section) 5

Compare meaning

How does mi5 compare to similar and commonly confused words? Explore the most common comparisons:

MI5 vs. MI6

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

A man who left a fake stick of dynamite outside the headquarters of MI5 has been found guilty of carrying out a bomb hoax.

From BBC

Pereira is then seen moving the object, propping it up against the MI5 HQ doors, with a green cigarette lighter positioned nearby.

From BBC

When giving evidence, Pereira insisted the device he left outside MI5 would not have been mistaken for an explosive, but added: "The news inside was dynamite."

From BBC

"The defendant attended Thames House in Millbank, knowing it to be the headquarters of the security services MI5," added Revel.

From BBC

Giving evidence, Pereira said he left the object at the front of MI5 because he wanted to "catch the attention" of the security services.

From BBC

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023