What's a Short ?
Shorts are a garment worn over the pelvic area, circling the waist and splitting to cover the upper part of the legs, sometimes extending down to the knees but not covering the entire length of the leg. They are called "shorts" because they are a shortened version of trousers, which cover the entire leg, but not the foot. Shorts are typically worn in warm weather or in an environment where comfort and air flow are more important than the protection of the legs.
There are a variety of shorts, ranging from knee-length short trousers that can in some situations be worn as formal clothes to beachwear and athletic shorts. Some types of shorts are typically worn by women, such as culottes, which are a divided skirt resembling a pair of loose-cut shorts.
Terminological differences between Shorts
The British English term, short trousers, is used, only for shorts that are a short version of ordinary trousers (i.e., pants or slacks in American English). For example: tailored shorts, often lined, as typically worn as part of a school uniform for boys up to their early teens, and by servicemen and policemen in tropical climates. Shorts, used unqualified in British English, refers to sports shorts, athletic shorts, or casual shorts; the last is nowadays commonplace in warm weather in the UK. Shorts are also known as "half pants" in India.
The American English term, short pants, is probably the nearest equivalent in the U.S., where they might now be called dress shorts, a term that has not gained much currency in Britain.
A somewhat similar garment worn by men in Australia is called stubbies.
The term, boxer shorts, is an American coinage for a particular kind of men's underwear, and is now also common in Britain. However, boxer shorts are often referred to merely as boxers in the USA. Moreover, whereas the American English usage of the word pants refers to outerwear (i.e., trousers in British English), the usage of pants in British English refers to the garment worn under one’s trousers, such as boxers; such a garment, however, is referred to as underpants in American English (note the qualification of the word pants by the word under).
Source : Shorts Wikipedia