Phrase guide

if and only if

conj · 2 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

Each Play button uses your device's default local English voice, or a natural local fallback. The selected voice name appears after playback. This is synthesized speech, not a source recording.

  • UK: /ɪf ən(d)ˈəʊn.li ɪf/
  • US: /ɪf ən(d)ˈoʊn.li ɪf/
  • Southern-England: Recorded audio is listed in the source snapshot.
  • US: Recorded audio is listed in the source snapshot.

1

conj

Meaning 1

Is equivalent to; implies and is implied by; is true and false in the same cases as.

Definition source: English Wiktionary via Wiktextract

Topics: human-sciences, logic, mathematics, philosophy, sciences

Examples

  • 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.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

2

conj

Meaning 2

Synonym of if (with added intensity)

Definition source: English Wiktionary via Wiktextract

Usage: broadly, informal

Examples

  • I'll let you go to the concert if and only if you clean your room.

Meaning relationships

Synonyms: if

Antonyms: none provided

History

Etymology

No etymology was provided for this word.

Across languages

Translations

41 source translations are retained for this English entry.

  • Arabic: شَرْطَ أَنّ (šarṭa ʔann) — implies and is implied by
  • Arabic: فَقَط إِذَا (faqaṭ ʔiḏā) — implies and is implied by
  • Arabic: شَرِيطَةً أَنَّ (šarīṭatan ʔanna) — implies and is implied by
  • Arabic: فَقَط فِي حَالَة (faqaṭ fī ḥāla) — implies and is implied by
  • Arabic: بشرط إن (bešarṭ ʔenn) — implies and is implied by
  • Arabic: بس لو — implies and is implied by
  • Basque: baldin eta soilik baldin — implies and is implied by
  • Catalan: si i només si — implies and is implied by
  • Chinese Mandarin: 當且僅當 /当且仅当 (dāngqiějǐndāng) — implies and is implied by
  • Chinese Mandarin: 若且唯若 (ruòqiěwéiruò) — implies and is implied by
  • Czech: právě tehdy, když — implies and is implied by
  • Danish: hvis og kun hvis — implies and is implied by
  • Dutch: dan en slechts dan als — implies and is implied by
  • Dutch: als en slechts als — implies and is implied by
  • Esperanto: se kaj nur se — implies and is implied by
  • Finnish: jos ja vain jos — implies and is implied by
  • French: si et seulement si — implies and is implied by
  • Georgian: მხოლოდ იმ შემთხვევაში, თუ (mxolod im šemtxvevaši, tu) — implies and is implied by
  • German: genau dann, wenn — implies and is implied by
  • German: dann und nur dann, wenn — implies and is implied by
  • Greek: αν και μόνο αν (an kai móno an) — implies and is implied by
  • Hebrew: אם ורק אם (im ve-rak im) — implies and is implied by
  • Hungarian: akkor és csakis akkor, ha — implies and is implied by
  • Icelandic: ef og aðeins ef — implies and is implied by
  • Icelandic: þá og því aðeins að — implies and is implied by
  • Irish: is gá agus is leor — implies and is implied by
  • Italian: se e solo se — implies and is implied by
  • Lithuanian: tada ir tik tada — implies and is implied by
  • Macedonian: ако и само ако (ako i samo ako) — implies and is implied by
  • Persian: اگر و فقط اگر (agar va faqat agar) — implies and is implied by
  • Polish: wtedy i tylko wtedy — implies and is implied by
  • Portuguese: se e somente se — implies and is implied by
  • Romanian: dacă și numai dacă — implies and is implied by
  • Russian: тогда́ и то́лько тогда́ — implies and is implied by
  • Slovene: če in samo če — implies and is implied by
  • Spanish: si y sólo si — implies and is implied by
  • Swedish: om och endast om — implies and is implied by
  • Thai: ก็ต่อเมื่อ — implies and is implied by
  • Turkish: ancak ve ancak — implies and is implied by
  • Vietnamese: khi và chỉ khi — implies and is implied by
  • Vietnamese: nếu và chỉ nếu — implies and is implied by