Deuteronomy 22:5
The woman shall not wear that which pertaineth unto a man, neither shall a man put on a woman’s garment: for all that do so are abomination unto the LORD thy God. The woman shall not wear that which pertaineth unto a man, neither shall a man put on a woman’s garment: for all that do so are abomination unto the LORD thy God.
The verse forbids a woman to wear what belongs to a man and forbids a man to put on a woman's garment, requiring a clear and visible distinction between male and female dress. Keeping that distinction is God's order and a direction He considers important and explicit, so disregarding it reverses His order and makes those who do so an abomination to Him and guilty of a serious violation of His direction. Dress that disregards the distinction is immodest apparel and is unfitting for Christ's followers, especially for women professing to follow Christ, and a woman's adoption of men's-like clothing undermines her influence.
The distinction matters because shared or interchangeable dress would cause confusion and increase crime. The verse rejects the American costume and any dress-reform style that imitates the opposite sex and removes or erases the distinction between the sexes. That condemned style is specifically a woman's outfit closely resembling men's clothing in the form of vest with pants and a coatlike dress.
The verse does not require retaining unhealthy or impractical women's clothing, but allows modest dress to be changed to be healthful, comfortable, and convenient while preserving the male-female distinction. That preservation of distinction is what distinguishes the approved practical reform dress, which is comfortable, convenient, and healthful, from the condemned costume.