mukhannaths—effeminate men.

A woman who emulates men likewise absorbs their traits, so that she begins to indulge in conspicuous display and public prominence, adopting masculine ways to the point that some of them uncover their bodies as men do, seek to dominate men as men dominate women, and engage in actions that contradict the modesty and reserve the Law prescribes for women. All of this may come about through imitation alone.

Once it is clear that there must be a visible difference between the clothing of men and that of women, and that women’s dress must provide the concealment and seclusion that fulfill this aim, the root principle of the matter becomes plain: if a garment is, for the most part, men’s attire, a woman is forbidden to wear it—even though it covers—such as the farajī (a loose outer cloak) that in certain lands is worn by men but not by women. The prohibition of such garments shifts as customs shift. Where the distinction turns on the very degree of covering, women are instructed to choose whatever most effectively conceals … and even if the outward differentiation could, in theory, be achieved without that extra cover, whenever a garment combines scant concealment with resemblance to men it is forbidden on both counts. Allah knows best.