The surface endings of دَاعٍ and رَامٍ look similar, although the underlying roots differ: د ع و versus ر م ي.
RootImperfectActive participle
د ع ويَدْعُودَاعٍ
ر م ييَرْمِيرَامٍ
The loss of yāʾ in an indefinite nominative/genitive participle is not a universal rule for every case or definiteness. الدَّاعِي and الرَّامِي retain yāʾ.
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Defective Verbs: Six Iʿlāl Rules and Four Short Paradigms
The surface endings of دَاعٍ and رَامٍ look similar, although the underlying roots differ: د ع و versus ر م ي.
RootImperfectActive participle
د ع ويَدْعُودَاعٍ
ر م ييَرْمِيرَامٍ
The loss of yāʾ in an indefinite nominative/genitive participle is not a universal rule for every case or definiteness. الدَّاعِي and الرَّامِي retain yāʾ.