Identification, Friend or Foe: a system of transmitters and transponders that uses coded signals to distinguish between friendly and hostile aircraft.
iff
Mathematics
1.
if and only if.
Examples from the web for IFF
A person is a bachelor IFF that person is a marriageable man who has never married.
British Dictionary definitions for IFF
iff
/ɪf/
conjunction
1.
(logic) a shortened form of if and only if: it indicates that the two sentences so connected are necessary and sufficient conditions for one another. Usually iff is used for equivalence in the metalanguage, rather than as the biconditional in the object language
IFF
abbreviation
1.
Identification, Friend or Foe: a system using radar transmissions to which equipment carried by friendly forces automatically responds with a precoded signal
mathematics, logic if and only if, i.e. necessary and sufficient. For example, two figures are congruent iff one can be placed over the other so that they coincide. (2002-12-28)