How sound is the saying, "Whoever casts off the garment of modesty has no backbiting due to him," and is it permissible to backbite an immodest woman regarding what she wears, and what is the ruling on describing her as a whore?

It is permissible to mention what an unveiled woman has openly committed of فسق (immorality/transgression), and this is known as public exposure (تشهير). For the one who openly commits فسق, it is permissible to backbite him and expose him for what he has openly committed, but not for what he has not openly committed. And whoever casts off the garment of modesty, there is no backbiting for him. As for describing an unveiled woman as a harlot ('aahirah), it is not permissible. Scholars have differed as to whether it is an explicit accusation (qadhf sareeh) or an implicit one (kinayah). Some consider it an explicit accusation that necessitates the prescribed punishment (hadd), while others consider it an implicit accusation that necessitates the prescribed punishment if the intention was accusation, and discretionary punishment (ta'zeer) if it was not. The meanings of words are subject to customary usage and current contextual clues.