iff
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\ ˈif-ᵊn(d)-ˈōn-lē-ˌif 
; ˈif, sometimes read with a prolonged f \
; ˈif, sometimes read with a prolonged f \Definition of iff
(Entry 1 of 2)
: if and only if
two figures are congruent iff one can be placed over the other so that they coincide —used in logic and mathematics
IFF
abbreviationDefinition of IFF (Entry 2 of 2)
identification, friend or foe
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The first known use of iff was in 1955
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