Grammar term · Sarf · morphology
أَجْوَف
ajwaf
Hollow root (weak middle)
Sarf · morphologyRoot soundness (sihha/i'lal)core term4,997+ in the Qur'an
In one line
The hollow root: a weak middle radical — قَالَ is really قول, كَانَ is كون — with the alif filling the gap.
Classical definition
الأَجْوَفُ مَا كَانَتْ عَيْنُهُ حَرْفَ عِلَّةٍ، كَقَالَ وَبَاعَ.
“The ajwaf is that whose middle radical is a weak letter, like qala and ba'a.”
(بتصرف من شذا العرف)
Key words in the Arabic
أَجْوَفhollow — weak in the middle
عَيْنُهُits middle radical
Understand it
The Qur'an's most frequent verbs live here: قَالَ (قول), كَانَ (كون), جَاءَ (جيء), زَادَ (زيد). The middle weak letter flips to alif in the madi (i'lal bil-qalb) and shortens whenever the ending closes the syllable: قَالَ but قُلْتُ, كَانَ but كُنْتُ. That long-short alternation is the ajwaf's signature, and recovering the real root (waw or ya?) is done through the mudari': يَقُولُ reveals قول, يَبِيعُ reveals بيع.
How to spot it
Recognition test
A three-letter madi with a long alif in the middle: ajwaf. Check the mudari' to recover the hidden waw or ya, and expect the vowel to shorten before sukun-starting endings.
In the Qur'an
وَكَانَ ٱللَّهُ غَفُورًا رَّحِيمًا
An-Nisa 4:96 — “And Allah is ever Forgiving, Merciful”
كَانَ — root كون: the middle waw has flipped to alif; in كُنْتُمْ the hollow closes to a short vowel.
Forms it takes
أجوف واوييائيأجوف يائيواوي
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