Undergarments, also called underwear or sometimes intimate clothing, are clothes worn next to the skin, usually under other clothes. Wearing and changing underwear permits outer garments to be worn repeatedly without needing to be cleaned.
In addition to keeping outer garments from soiling, undergarments are worn for a variety of reasons: warmth, comfort and hygiene being the most common. Undergarments are often used for modesty or erotic display; sometimes both of these motivations are simultaneously present.
Undergarments can also have religious significance, as in the special temple garment worn by followers of the LDS Church (Mormons).
"Underwearing" (being in public wearing nothing but underwear)
Wearing just underwear in public is considered an intermediate form between being socially acceptably dressed and being nude. People are often arrested if found wearing only their underwear. Some prisons issue inmates specially dyed underwear, which often helps in catching escapees, who might strip off their prison jumpsuit and walk off a job site wearing only their underwear. Police response to underwearing depends on context. For example, in a public fountain that has been specifically designed for waterplay, it is often acceptable to run through it wearing only underwear, because of the recognized spontaneity of such activities on a hot day (e.g. people can't be expected to carry a bathingsuit with them everywhere they go). Thus cooling off in a fountain or lake is considered acceptable underwearing, because the underwearing serves a necessary purpose. Deliberate acts of underwearing are often done as a form of protest (e.g. "I'd rather be caught in my underwear than be caught wearing fur"). In such cases, the underwearers are usually thought of kindly, but end up getting off once the matters work their way though the court system. It is thus mainly the inconvenience of arrest that keeps underwearing under wraps. In other cases, corporations have used underwearing as a form of sensationalism for advertising. For example, freshpair.com had a number of models parading around New York's Times Square wearing nothing but their underwear. None of the models were arrested. Some feel that cops turning a "blind eye" to this activity is biased toward commerce (i.e. underwearers are OK as long as their cause is commerce, and not performance art or protest). Charges filed, pending arrest for underwearing are typically "disorderly conduct" rather than public indecency.
Of course a person is not underwearing when wearing only shirts and shorts that are designed to function as both underwear and outerwear.
Since there is no other word for underwearing, (i.e. nude, naked, and stripped usually refer to being completely naked), sometimes people who are wearing only underwear are referred to as naked. For example, the "naked cowboy" is a celebrity who often wears only underwear, boots, and a cowboy hat. In the Emperor's New Clothes, the emperor, wearing only his underwear, was referred to as "naked".
Historically T-shirts were originally considered underwear. Thus at one time, it was unacceptable to be seen in public in a T-shirt. People were required to wear at least two shirts in public: an outershirt, and an undershirt. More recently, T-shirts were re-interpreted as outerwear, and it is now acceptable to wear only one shirt in public.
These social constraints apply only to mixed-gendered spaces. For example, it is acceptable for a person to be with other people (of the same gender) when they are in a changeroom or other space that has been specifically designated for changing clothes.
Underpants are in British English also called pants. Women's underpants are also called knickers (British English) or panties (American English).
Two major types of men's underpants are the boxer short (shorts-length and loose) and the brief (smaller and tighter). The two are combined in the aptly-named boxer brief (long and tight). For performances, such as erotic dance, briefs are often preferred.
For more details and variations, see the Present Day section below.
For urinating the penis is either passed through a fly, or the front side of the underpants is lowered (they are flexible enough to do that without lowering the whole underpants). Even if a fly is present, it is a matter of preference which method is chosen.
undergarment worn next to the skin and under the outer garments.