• Faith Freedom International
  Faith Freedom International
  Faith Freedom International is a website that is critical of Islam. FFI identifies itself as "a grassroots worldwide movement of ex-Muslims and all those who are concerned about the rise of the Islamic threat"...
  
  , a website critical of Islam created by Ali Sina
• Fauna and Flora International
  Fauna and Flora Preservation Society
  Fauna & Flora International , formerly the Fauna and Flora Preservation Society, is an international conservation charity and non-governmental organization....
  
  , a conservation group
• Fatal familial insomnia
  Fatal familial insomnia
  Fatal familial insomnia is a very rare autosomal dominant inherited prion disease of the brain. It is almost always caused by a mutation to the protein PrPC, but can also develop spontaneously in patients with a non-inherited mutation variant called sporadic fatal insomnia...
  
  , a very rare inherited brain disease
• Fellow of the Flag Institute
  Flag Institute
  The Flag Institute is a research and documentation centre for flags and flag information, founded on St George's Day, 23 April 1971 by William Crampton and Captain EMC Barraclough CBE RN. Although not an official body, it is the principal advisor and designer of flags to the government of the...
  
  , a title
• ffi, a common typographical ligature
  Ligature (typography)
  In writing and typography, a ligature occurs where two or more graphemes are joined as a single glyph. Ligatures usually replace consecutive characters sharing common components and are part of a more general class of glyphs called "contextual forms", where the specific shape of a letter depends on...
  
  
• Foreign function interface
  Foreign function interface
  A foreign function interface is a mechanism by which a program written in one programming language can call routines or make use of services written in another. The term comes from the specification for Common Lisp, which explicitly refers to the language features for inter-language calls as...
  
  , an aid to interoperability between programming languages (Norwegian Defence Research Establishment
  Norwegian Defence Research Establishment
  The Norwegian Defence Research Establishment is a research institute that conducts research and development on behalf of the Norwegian Armed Forces and provides expert advice to political and military defence leaders...
  
  ), a Norwegian military R&D institute
• Franciscan Friars of the Immaculate
  Franciscan Friars of the Immaculate
  The Franciscan Friars of the Immaculate is a Roman Catholic Institute of Religious Life with Pontifical Right established by Pope John Paul II on 1 January 1998. The F.F.I. was founded by two Franciscan Conventual priests on 2 August 1970 and is a reformed Franciscan Conventual religious institute...
  
  , a Roman Catholic institute of religious life.
• French Forces of the Interior
  French Forces of the Interior
  The French Forces of the Interior refers to French resistance fighters in the later stages of World War II. Charles de Gaulle used it as a formal name for the resistance fighters. The change in designation of these groups to FFI occurred as France's status changed from that of an occupied nation...
  
   , French resistance fighters during World War II
• Fuel Freedom International
  Fuel Freedom International
  Fuel Freedom International is a multi-level marketing company based in Altamonte Springs, Florida and co-owned by Wendy Lewis and Randy Ray. It sells pills trade marked as MPG-CAPS, which are claimed to improve fuel economy, reduce emissions and increase engine power...
  
  , a multi-level marketing company based in Florida, USA
• Freefind Initiative, an organization dedicated to keeping kids active and away from trouble through playing sports.

In entertainment:

• Festival Film Indonesia, the Indonesian annual Film Festival
• Final Fantasy I
  Final Fantasy (video game)
  is a fantasy role-playing video game created by Hironobu Sakaguchi, developed and first published in Japan by Square in 1987. It is the first game in Square's Final Fantasy series...
  
  , the first video game in the Square RPG franchise
• Final Fight
  Final Fight
  is a side-scrolling beat-'em-up game originally released by Capcom as a coin-operated video game in . It was the seventh game released by Capcom for their CP System arcade game hardware...
  
  , a fighting action video game, sometimes abbreviated FFI to distinguish it from its sequels