Trousers or pants (North American English) are an item of clothing that might have originated in Central Asia, worn from the waist to the ankles, covering both legs separately (rather than with cloth extending across both legs as in robes, skirts, and dresses).

Outside North America, the word pants generally means underwear and not trousers.

Shorts are similar to trousers, but with legs that come down only to around the area of the knee, higher or lower depending on the style of the garment. To distinguish them from shorts, trousers may be called "long trousers" in certain contexts such as school uniform, where tailored shorts may be called "short trousers", especially in the UK.

The oldest known trousers were found at the Yanghai cemetery in Turpan, Xinjiang, western China and dated to the period between the 10th and the 13th centuries BC. Made of wool, the trousers had straight legs and wide crotches and were likely made for horseback riding.

In most of Europe, trousers have been worn since ancient times and throughout the Medieval period, becoming the most common form of lower-body clothing for adult males in the modern world. Breeches were worn instead of trousers in early modern Europe by some men in higher classes of society. Distinctive formal trousers are traditionally worn with formal and semi-formal day attire. Since the mid-20th century, trousers have increasingly been worn by women as well.

Jeans, made of denim, are a form of trousers for casual wear widely worn all over the world by both sexes. Shorts are often preferred in hot weather or for some sports and also often by children and adolescents. Trousers are worn on the hips or waist and are often held up by buttons, elastic, a belt or suspenders (braces). Unless elastic, and especially for men, trousers usually provide a zippered or buttoned fly. Jeans usually feature side and rear pockets with pocket openings placed slightly below the waist band. It is also possible for trousers to provide cargo pockets further down the legs.

Maintenance of fit is more challenging for trousers than for some other garments. Leg-length can be adjusted with a hem, which helps to retain fit during the adolescent and early adulthood growth years. Tailoring adjustment of girth to accommodate weight gain or weight loss is relatively limited, and otherwise serviceable trousers may need to be replaced after a significant change in body composition.

Terminology

In Scotland, trousers are occasionally known as trews, which is the historic root of the word trousers. Trousers are also known as breeks in Scots, a word related to breeches. The item of clothing worn under trousers is underpants. The standard form trousers is also used, but it is sometimes pronounced in a manner approximately represented by [ˈtruːzɨrz], as Scots did not completely undergo the Great Vowel Shift, and thus retains the vowel sound of the Gaelic truis from which the word originates.

In North America, Australia, South Africa and North West England pants is the general category term, whereas trousers (sometimes slacks in Australia and the United States) often refers more specifically to tailored garments with a waistband, belt-loops, and a fly-front. In these dialects, elastic-waist knitted garments would be called pants, but not trousers (or slacks).

North Americans call undergarments underwear, underpants, undies, or panties (the last are women's garments specifically) to distinguish them from other pants that are worn on the outside. The term drawers normally refers to undergarments, but in some dialects, may be found as a synonym for "breeches", that is, trousers. In these dialects, the term underdrawers is used for undergarments. Many North Americans refer to their undergarments by their type, such as boxers or briefs.

In Australia, men's underwear also has various informal terms including under-dacks, undies, dacks or jocks. In New Zealand men's underwear is known informally as undies or dacks.

The words trouser (or pant) instead of trousers (or pants) is sometimes used in the tailoring and fashion industries as a generic term, for instance when discussing styles, such as "a flared trouser", rather than as a specific item. The words trousers and pants are pluralia tantum, nouns that generally only appear in plural form—much like the words scissors and tongs, and as such pair of trousers is the usual correct form. However, the singular form is used in some compound words, such as trouser-leg, trouser-press and trouser-bottoms.

Jeans are trousers typically made from denim or dungaree cloth. Skin-tight leggings are commonly referred to as tights.

Types

There are several different main types of pants and trousers, such as dress pants, jeans, khakis, chinos, leggings, and sweatpants. They can also be classified by fit, fabric, and other features. There is apparently no universal, overarching classification.