Sarf · morphologyNumber & plural typecore term244+ in the Qur'an
Also written: Muthanna · Dual · Mufrad · Arabic number
In one line
The dual: add انِ (or يْنِ) and one word means exactly two — no 'and' needed.
Definition (modern)
الْمُثَنَّى هُوَ مَا دَلَّ عَلَى اثْنَيْنِ، أَوِ اثْنَتَيْنِ، وَأَغْنَى عَنِ الْمُتَعَاطِفَيْنِ. إِعْرَابُهُ: يُرْفَعُ بِالْأَلِفِ، وَيُنْصَبُ وَيُجَرُّ بِالْيَاءِ.
“The dual is what indicates two (masculine or feminine) and spares you the two conjoined words. Its i'rab: rafa' with alif, nasb and jarr with ya.”
(النحو التطبيقي)
Key words in the Arabic
أَغْنَى عَنِspares you, replaces
الْمُتَعَاطِفَيْنِthe two joined by 'and'
Understand it
The pin's phrase أَغْنَى عَنِ الْمُتَعَاطِفَيْنِ is the whole idea: مُسْلِمَانِ says مُسْلِمٌ وَمُسْلِمٌ in one word. Its i'rab runs on letters, not vowels — الطَّالِبَانِ came, رَأَيْتُ الطَّالِبَيْنِ, مَرَرْتُ بِالطَّالِبَيْنِ — so nasb and jarr look identical and only the alif of rafa' stands apart. The نِ on the end drops in idafa: يَدَا زَيْدٍ.
How to spot it
Recognition test
A noun ending ـَانِ in rafa' or ـَيْنِ elsewhere, meaning exactly two. Distinguish the ـَيْنِ of the dual (fatha before ya) from the ـِينَ of the sound plural (kasra before ya).
In the Qur'an
وَدَخَلَ مَعَهُ ٱلسِّجْنَ فَتَيَانِ
Yusuf 12:36 — “And two young men entered the prison with him”
فَتَيَانِ is fa'il in rafa' — shown by the alif, the dual's rafa' letter.
Don't confuse it with
Words like سَلْمَان، بُسْتَان، لِسَان end in ان without being dual. A genuine dual ends ـَانِ with kasra on the nun — with the vowel marks present, as they are throughout the mushaf, the difference is immediate.
Related terms
▶ Watch the lessons
From the free course The Language of Quran — Easier than English (Book 1) (LoQ1), taught by Ustad Muhammad Arjan Ali.
Common questions
How is the dual different from just saying “two”?
Arabic can say اِثْنَانِ but rarely needs to: مُسْلِمَانِ is “two Muslims” in one word. A ta marbuta becomes a regular ta before the suffix: مَدْرَسَةٌ → مَدْرَسَتَانِ.
Domain: Sarf · Category: Number & plural type · Frequency in the Qur'an: 244 · Source: النحو التطبيقي, cross-checked against the Quranic corpus · Reviewed by Ustad M. Arjan Ali