Cause of Ghayr Munsarif: Sighat Muntaha al-Jumu'

1. Not Every Plural Is Ghayr Munsarif

Plurality by itself is not enough. In this topic, a plural becomes ghayr munsarif when it has the form called صِيغَةُ مُنْتَهَى الْجُمُوعِ. This form stands for two causes.

2. What Is Sighat Muntaha al-Jumu'?

It is a broken-plural shape in which the plural alif is followed by two letters, as in دَوَابُّ and مَسَاجِدُ, or by three letters whose middle letter is sakin, as in مَسَاكِينُ. In دَوَابُّ, the shaddah represents two letters. The decision depends on the form of the word, not merely on its meaning as “more than one.”

3. First Established Pair

دَابَّةٌ → دَوَابُّ

دَوَابُّ is the plural of دَابَّةٌ. Its form belongs to صيغة منتهى الجموع, so it is ghayr munsarif and does not take tanwin.

4. Two More Established Pairs

- مَسْجِدٌ → مَسَاجِدُ
- مِسْكِينٌ → مَسَاكِينُ

In both plurals, the form is صيغة منتهى الجموع. Therefore مَسَاجِدُ and مَسَاكِينُ are ghayr munsarif.

5. A Broken Plural Is Not Automatically Diptote

Compare مَسَاجِدُ with كُتُبٌ. Both are broken plurals, but مَسَاجِدُ has the required صيغة منتهى الجموع form and is ghayr munsarif. كُتُبٌ does not have that form, so it remains declinable and takes tanwin.

6. Form Can Matter Even Without Plural Meaning

Some lexical items are treated as singular words but match a صيغة منتهى الجموع form. They are also ghayr munsarif because of their form: طَمَاطِمُ (tomato) and جَمَاشِيرُ (whip). The deciding point is the recognized form, not merely plural meaning.

7. Read the Ending in Context

- هٰذِهِ مَسَاجِدُ — nominative: one dammah, no tanwin.
- رَأَيْتُ مَسَاجِدَ — accusative: one fathah.
- مَرَرْتُ بِمَسَاجِدَ — basic genitive: one fathah.

With ال or idafah, the genitive kasrah returns: فِي الْمَسَاجِدِ; فِي مَسَاجِدِ الْمَدِينَةِ.

8. A Safe Decision Route

1. Confirm whether the word has the taught صيغة منتهى الجموع form.
2. Do not classify every broken plural alike: مَسَاجِدُ differs from كُتُبٌ.
3. Remember that a singular lexical item may still be diptote because of this form: طَمَاطِمُ، جَمَاشِيرُ.
4. Apply the familiar al/idafah genitive exception when present.