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 "sex-up" 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.
Undress codes that prohibit clothing altogether are less common and are limited to naturist recreation facilities, and to saunas and steam baths, where the cultural traditions of a country encourage or require nudity, for example in Germany, Austria, Denmark, Sweden, Finland and Estonia.
The social norm in some countries is to wear considerably less or briefer clothing than in others. Fashions since the mid-20th century has been towards briefer, more form-fitting styles, as well as thinner and sheer materials. In some cultures, including some in Africa, Latin America and South-East Asia/Oceania, traditional dress consists of less clothing than those of the West. Some religious traditions or rituals require the members to be nude, as was the case with the ancient Indian Gymnosophists or the Christian sect of the Adamites (the custom is still practised by ascetics of certain Indian religions, as in Jainism). (see also Christian naturism).
Laws in many countries require a person to undress in some circumstances when requested by a customs or police officer in a strip search.