if and only if

English

Conjunction

if and only if

1. (logic, mathematics) Is equivalent to; implies and is implied by; is true and false in the same cases as.

   A rectangle is a square if and only if all four of its sides have the same length.

   An integer is even if and only if its square is also even.

2. (by extension, informal) Synonym of if (with added intensity) (Can we add an example for this sense?)

Hypernyms

• logical connective

Related terms

• if
• if and when
• iff
• only if

Translations

implies and is implied by

• Arabic: شَرْطَ أَنّ (šarṭa ʔann), فَقَط إِذَا (faqaṭ ʔiḏā), شَرِيطَةً أَنَّ (šarīṭatan ʔanna), فَقَط فِي حَالَة (faqaṭ fī ḥāla)

  Egyptian Arabic: بشرط إن (bešarṭ ʔenn), بس لو (bass law)

• Basque: baldin eta soilik baldin
• Catalan: si i només si
• Chinese:

  Mandarin: 當且僅當 / 当且仅当 (zh) (dāngqiějǐndāng) (Mainland China), 若且唯若 (zh) (ruòqiěwéiruò) (Taiwan)

• Czech: právě tehdy, když
• Danish: hvis og kun hvis
• Dutch: dan en slechts dan als (Netherlands), als en slechts als (Belgium)
• Esperanto: se kaj nur se
• Finnish: jos ja vain jos (fi)
• French: si et seulement si (fr)
• Georgian: მხოლოდ იმ შემთხვევაში, თუ (mxolod im šemtxvevaši, tu)
• German: genau dann, wenn, dann und nur dann, wenn
• Greek: αν και μόνο αν (el) (an kai móno an)
• Hebrew: אם ורק אם (he) (im ve-rak im)
• Hungarian: akkor és csakis akkor, ha
• Icelandic: ef og aðeins ef, þá og því aðeins að
• Irish: is gá agus is leor
• Italian: se e solo se
• Lithuanian: tada ir tik tada
• Persian: اگر و فقط اگر (agar va faqat agar)
• Polish: wtedy i tylko wtedy
• Portuguese: se e somente se
• Romanian: dacă și numai dacă
• Russian: тогда́ и то́лько тогда́(, когда́ ...) (togdá i tólʹko togdá(, kogdá ...))
• Slovene: če in samo če
• Spanish: si y sólo si (es)
• Swedish: om och endast om (sv)
• Thai: ก็ต่อเมื่อ
• Turkish: ancak ve ancak (tr)
• Vietnamese: khi và chỉ khi, nếu và chỉ nếu

See also

• ↔, ⇔