Young Girl In Shorts

Shorts are a bifurcated garment worn by both men and women over their pelvic area, circling the waist, and covering the upper part of the legs, sometimes extending down to or even below the knee, but not covering the entire length of the leg, either as outer or undergarment, which makes them comfortable and easy to wear. They are called "shorts" because they are a shortened version of trousers, which cover the entire leg.
Transatlantic terminological confusions
In British English the term "short trousers" is used, but only for shorts that are a short version of real trousers, e.g. tailored shorts, often lined, as typically worn as part of school uniform for boys up to their early-to-middle teens from roughly 1920 to 1980 (and still in Australia, Singapore, New Zealand and South Africa), and by servicemen and policemen posted overseas to tropical climates. The American-English term "short pants" is probably the nearest equivalent. In the US, these might nowadays be called "dress shorts" or "walk shorts", terms which have not gained currency in Britain. A somewhat similar garment worn by men in Australia is called "stubbies". "Shorts" is used unqualified in British English to refer to sports shorts, athletic shorts, or casual shorts, the latter nowadays being, in the United Kingdom itself, commonplace in warm weather.