مَرْضِيٌّ
Translation: Approved of / acceptable.
The passive-participle pattern combines with a weak final wāw. Substitution brings that weak consonant into a yāʾ sequence; assimilation produces the final doubled يّ.
FormRoleVisible feature
رَاضٍActive participleFinal yāʾ omitted in indefinite nominative
مَرْضِيٌّPassive participleGeminated yāʾ
رَاضِيَةٌFeminine active participleYāʾ visible
مَرْضِيَّةٌFeminine passive participleGeminated yāʾ remains
Idghām merges corresponding consonants into a doubled sound; it is not merely deleting a letter.