Grammar term · Sarf · morphology
إِبْدَال
ibdal
Letter replacement (ibdal)
Sarf · morphologyMorphophonemic processadvanced term458+ in the Qur'an
In one line
Consonant swapping: one letter replaces another for smoothness — the ta of افْتَعَلَ becomes ط after ص: اصْطَبَرَ.
Classical definition
الإِبْدَالُ جَعْلُ حَرْفٍ مَكَانَ حَرْفٍ آخَرَ، كَإِبْدَالِ تَاءِ الافْتِعَالِ دَالًا فِي ازْدَجَرَ.
“Ibdal is the placing of one letter in the position of another, like the ta of ifti'al becoming dal or ta becoming emphatic.”
(بتصرف من شذا العرف)
Key words in the Arabic
جَعْلُ حَرْفٍ مَكَانَ حَرْفٍputting one letter for another
تَاء الافْتِعَالthe ta of the ifti'al pattern
Understand it
Where i'lal reworks weak letters, ibdal swaps strong ones. The showcase is Form VIII (افْتَعَلَ): its ta refuses to sit politely after emphatic or voiced letters, becoming ط after ص/ض/ط/ظ (صَبَرَ → اصْطَبَرَ) and د after د/ذ/ز (زَحَمَ → ازْدَحَمَ); after و the two merge to تّ (وَقَى → اتَّقَى). Spot the pattern and apparently root-less words hand over their roots.
How to spot it
Recognition test
A Form VIII verb whose expected ta shows up as ط، د or a doubled تّ: ibdal. Undo the swap to recover the root: اصْطَبَرَ → صبر, اتَّقَى → وقي.
In the Qur'an
وَٱصْطَبِرْ لِعِبَٰدَتِهِۦ
Maryam 19:65 — “and be steadfast in worshipping Him”
اصْطَبِرْ — Form VIII of صَبَرَ: the pattern's ta has become ط beside the emphatic sad — ibdal.
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