An undress

An undress code is a dress code or social norm which sets an upper limit on the amount of clothing that can or should be worn. For example, some public swimming facilities set maximum clothing standards, for sanitary reasons. These rules restrict persons using the facilities to specific types of bathing suits.

Historically, the term "undress" is used to describe dress codes consisting of clothes of formality much less than those normally worn, including everything from dressing gowns, to, in their first few decades, lounge suits In contrast, the term "overdress" can describe the wearing of clothing which is more formal than that normally worn in that situation, and can in fact be more revealing, as in the case of evening gowns or cocktail dresses.

In some occupations, it is expected for the service provider to be under-dressed. Some employers require their service staff to be under-dressed. This may be a work requirement or a work culture. Some employers achieve this objective by providing a uniform which is more revealing than it needs to be.

Promoters of the entertainment industry, including sport, attempt to  the entertainment by under-dressing the entertainers or sportspeople. For example, in 1999, the beach volleyball regulatory body set a limit on the amount of clothing allowed for the athletes to wear during competition. These require only swimsuits as uniforms for women. This has led to some controversy.Similarly, organisers of some swimsuit competitions set a low maximum threshold for swimwear for contestants.