Semi-formal wear in the context of Suit (clothing)

A suit, also called a lounge suit, business suit, dress suit, or formal suit, is a set of clothes comprising a suit jacket and trousers of identical textiles generally worn with a collared dress shirt, necktie, and dress shoes. A skirt suit is similar, but with a matching pencil skirt instead of trousers. It is currently considered semi-formal wear or business wear in contemporary Western dress codes; however, when the suit was originally developed it was considered an informal or more casual option compared to the prevailing clothing standards of aristocrats and businessmen. The lounge suit originated in 19th-century Britain as sportswear and British country clothing, which is why it was seen as more casual than citywear at that time, with the roots of the suit coming from early modern Western Europe formal court or military clothes. After replacing the black frock coat in the early 20th century as regular daywear, a sober one-coloured suit became known as a lounge suit.

Suits are offered in different designs and constructions. Cut and cloth, whether two- or three-piece, single- or double-breasted, vary, in addition to various accessories. A two-piece suit has a jacket and trousers; a three-piece suit adds a waistcoat. Hats were almost always worn outdoors (and sometimes indoors) with all men's clothes until the counterculture of the 1960s in Western culture. Informal suits have been traditionally worn with a fedora, a trilby, or a flat cap. Other accessories include handkerchief, suspenders or belt, watch, and jewelry.

A waistcoat (UK and Commonwealth, /ˈweɪs(t)koʊt/ or /ˈwɛskət/; colloquially called a weskit) or vest (US and Canada) is a sleeveless upper-body garment. It is usually worn over a dress shirt and necktie and below a coat as a part of most men's formal wear. It is also sported as the third piece in the traditional three-piece male suit. Any given waistcoat can be simple or ornate, or for leisure or luxury. Historically, the waistcoat can be worn either in the place of, or underneath, a larger coat, dependent upon the weather, wearer, and setting.

Daytime formal wear and semi-formal wear commonly comprises a contrastingly coloured waistcoat, such as in buff or dove gray, still seen in morning dress and black lounge suit. Traditionally, a white waistcoat is worn for white tie and a black one for black tie.

Casual wear (or casual attire or clothing) is a Western dress code that is relaxed, occasional, spontaneous and suited for everyday use. Casual wear became popular in the Western world following the counterculture of the 1960s. When emphasising casual wear's comfort, it may be referred to as leisurewear or loungewear.

While casual is "informal" in the sense of "not formal", informal wear traditionally refers to a Western dress code associated with suits—a step below semi-formal wear—thus being more formal than casual attire.

Black tie is a semi-formal Western dress code for evening events, originating in British and North American conventions for attire in the 19th century. In British English, the dress code is often referred to synecdochically by its principal element for men, the dinner suit or dinner jacket. In American English, the equivalent term tuxedo (or tux) is common. The dinner suit is a black, midnight blue or white two- or three-piece suit, distinguished by satin or grosgrain jacket lapels and similar stripes along the outseam of the trousers. It is worn with a white dress shirt with standing or turndown collar and link cuffs, a black bow tie, sometimes an evening waistcoat or a cummerbund, and black patent leather dress shoes or court pumps. Accessories may include a semi-formal homburg, bowler, or boater hat. In Britain, some individuals may rebel from the formal dress code by wearing coloured socks or a bow tie that is not black, such as red. For women, an evening gown or other fashionable evening attire may be worn.

The first dinner jacket is traditionally traced to 1865 on the then Prince of Wales, later King Edward VII (1841–1910). The late 19th century saw gradual introduction of the lounge jacket without tails as a less formal and more comfortable leisure alternative to the frock coat. Thus in many non-English languages, a dinner jacket is still known as the false friend "smoking". In American English, its synonym "tuxedo" was derived from the village of Tuxedo Park in New York State, where it was introduced in 1886 following the example of Europeans. Following the counterculture of the 1960s, black tie has increasingly replaced white tie for more formal settings in the United States, along with cultures influenced by American culture.

Mess dress uniform is the most formal (or semi-formal, depending on the country) type of evening-wear uniform used by military personnel, police personnel, and other uniformed services members. It frequently consists of a mess jacket, trousers, white dress shirt and a black bow tie, along with orders, medals, and insignia. Design may depend on regiment or service branch, e.g. army, navy, air force, marines, etc. In modern Western dress codes, mess dress uniform is the supplementary alternative equivalent to the civilian black tie for evening wear. Mess dress uniforms are typically less formal than full dress uniform, but more formal than service dress uniform.

Prior to World War II, this style of military uniform was largely restricted to the British and United States Armed Forces, although the French, German, Swedish and other navies had adopted their own versions of mess dress during the late 19th century, influenced by the British Royal Navy.