F91 may refer to :
*
F91 Dudelange, a football club, based in Dudelange in southern Luxembourg
* ''
Mobile Suit Gundam F91
is a 1991 anime film. It was ''Gundam'' creator Yoshiyuki Tomino's attempt to launch a new ''Gundam'' saga, set 30 years after ''Char's Counterattack''. He re-teamed with character designer Yoshikazu Yasuhiko and mecha designer Kunio Okawara for ...
'', a 1991 animated film
*
HMS Brazen (F91)
HMS ''Brazen'' was a Type 22 frigate of the Royal Navy. She was completed three months ahead of schedule due to the Falklands War.
Royal Navy service
''Brazen'' served on the Armilla Patrol which became a task force during the Gulf War as par ...
, a 1981 British Royal Navy Type 22 frigate
*
HMS Murray (F91), a British Royal Navy Blackwood class second-rate anti-submarine frigate
* Republic
XF-91 Thunderceptor, a rocket-jet hybrid interceptor
*
Casio F-91W
The Casio F-91W is a digital watch manufactured by Japanese electronics company Casio. Introduced in 1989 as a successor of the F-87W, it is popular for its low price and long battery life. As of 2011, annual production of the watch is 3 mi ...
, a common and inexpensive digital watch, claimed by some to be associated with
terrorism
Terrorism, in its broadest sense, is the use of criminal violence to provoke a state of terror or fear, mostly with the intention to achieve political or religious aims. The term is used in this regard primarily to refer to intentional violen ...
* The
McCarthy 91 function
The McCarthy 91 function is a recursive function, defined by the computer scientist John McCarthy as a test case for formal verification within computer science.
The McCarthy 91 function is defined as
:M(n)=\begin
n - 10, & \mboxn > 100\mbox ...
, a recursively defined mathematical function
and also:
*
Conduct disorders
Conduct disorder (CD) is a mental disorder diagnosed in childhood or adolescence that presents itself through a repetitive and persistent pattern of behavior that includes theft, lies, physical violence that may lead to destruction, and reckles ...
ICD-10 code
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