Grammar term · I'rab · i'rab
ثُبُوت النُّون
thubut al-nun
Retention of nun (5 verbs/dual/m-pl)
I'rab · i'rabI'rab marker (alama)advanced term2,600+ in the Qur'an
In one line
Retention of the nun — the raf' marker of the five verbs.
Classical definition
وَأَمَّا النُّونُ فَتَكُونُ عَلَامَةً لِلرَّفْعِ فِي الْفِعْلِ الْمُضَارِعِ إِذَا اتَّصَلَ بِهِ ضَمِيرُ تَثْنِيَةٍ أَوْ ضَمِيرُ جَمْعٍ أَوْ ضَمِيرُ الْمُؤَنَّثَةِ الْمُخَاطَبَةِ.
“The nun is the marker of raf' in the present verb when the dual pronoun, the plural pronoun, or the pronoun of the addressed woman is joined to it.”
(الآجرّومية)
Understand it
In the five verbs the familiar damma is impossible, so the nun itself carries raf': يَعْمَلُونَ is marfu' because its nun stands. The moment أَنْ or لَمْ arrives the nun goes — تَعْمَلُوا — and its absence becomes the new marker. One letter, the whole story.
How to spot it
Recognition test
ـونَ / ـانِ / ـينَ intact on a mudari' = raf'.
Related terms