iff

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Mathematics.

if and only if.

IFF

Military.

Identification, Friend or Foe: a system of transmitters and transponders that uses coded signals to distinguish between friendly and hostile aircraft.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for iff

Contemporary Examples of iff

Historical Examples of iff

  • I could like her better, iff she was better to my young lady.

    Clarissa, Volume 3 (of 9)

    Samuel Richardson

  • But that same reseit, iff your Honner so please, to cure a shrewish wife.

    Clarissa, Volume 3 (of 9)

    Samuel Richardson

  • And what wold ye doe with my bryde soe gay, Iff I did sell her thee?

  • “He has his troubles,” quoth Mr. Iff cheerfully, if vaguely.

    The Bandbox

    Louis Joseph Vance

  • A friend of Miss Landis and also—curiously—in the same room with Mr. Iff.

    The Bandbox

    Louis Joseph Vance


British Dictionary definitions for iff

iff

conjunction

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 for

Identification, Friend or Foe: a system using radar transmissions to which equipment carried by friendly forces automatically responds with a precoded signal
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