- if and only if.
- 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. 2018
Examples from the Web for iff
The IFF, however, is not exactly an organization to be proud of.The Real Jersey Dictionary, Vol. 2
October 21, 2010
I could like her better, iff she was better to my young lady.
But that same reseit, iff your Honner so please, to cure a shrewish wife.
And what wold ye doe with my bryde soe gay, Iff I did sell her thee?A Book of Ballads, Volume 1
“He has his troubles,” quoth Mr. Iff cheerfully, if vaguely.
A friend of Miss Landis and also—curiously—in the same room with Mr. Iff.
- 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
- Identification, Friend or Foe: a system using radar transmissions to which equipment carried by friendly forces automatically responds with a precoded signal