In the Western world, dresses and/or skirts are women's clothing. Consider these statutes from the State of California:
California Code - Section 12947.5:
(a) "It shall be an unlawful employment practice for an employer to refuse to permit an employee to wear pants on account of the sex of the employee."
Of course, this is question begging. If skirts/dresses were not "women's clothing," why would some employers be forcing women to wear them, and what motivation would there be for the California legislature to grant women legal protection to wear pants?
Likewise, AB 196, another California statute provides legal protection to transgender men who wish to wear skirts/dresses, requiring that "that each employee be permitted to dress in accordance with the employee’s gender identity."
In conclusion, the California Code of Law provides legal protection to women who do
not wish to wear dresses and/or skirts as well as legal protection to men who
do wish to wear dresses and/or skirts.
For traditional Catholics, the teaching of Saint Thomas Aquinas is clear:
"As stated in the foregoing Article, outward apparel should be consistent with the estate of the person, according to the general custom. Hence it is in itself sinful for a woman to wear man's clothes, or vice versa; especially since this may be a cause of sensuous pleasure; and it is expressly forbidden in the Law (Deuteronomy 22) because the Gentiles used to practice this change of attire for the purpose of idolatrous superstition. Nevertheless this may be done sometimes without sin on account of some necessity, either in order to hide oneself from enemies, or through lack of other clothes, or for some similar motive." (Summa Theologica, IIa IIae, q.169, a.2, ad 3)