The source presents Ism Dharf in a three-form grid:
FormNumber
مَفْعَلٌSingular
مَفْعَلَانِDual
مَفَاعِلُPlural
The plural shown here is a broken-plural pattern, not a simple suffix added to the singular.
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The Three-Form Ism Dharf Grid
Derived Nouns: Noun of Place and Time (Ism Dharf)
The source presents Ism Dharf in a three-form grid:
FormNumber
مَفْعَلٌSingular
مَفْعَلَانِDual
مَفَاعِلُPlural
The plural shown here is a broken-plural pattern, not a simple suffix added to the singular.