if and only if (iff)
agar va ivâz agar, ~ ~ tanhâ ~
Fr.: si et seulement si
Logic, Math.: An → expression indicating that two → statements so connected are → necessary and sufficient conditions for one another. The corresponding logical symbols usually used are: ↔, ⇔, ≡, and iff.
ivâz, tanhâ (#)
An adverb meaning without others or anything further; alone; solely; exclusively. → if and only if.
M.E., from O.E. anlic, from ân, → one.
Ivâz, from Mid.Pers. êvâz/êvâc, from Proto-Iranian
*aiua-ka-; cf. Pers. yek,