Young Girl In Shorts

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.
Matters are further complicated by the fact that "shorts" in American English can refer to underwear, which is not the case in British English (except for the compound term "boxer shorts," a long-time American coinage recently gaining in Britain). Conversely, the word "pants" refers to outerwear (= trousers) in American usage (except when modified into "underpants") but when used unqualified in British English usually means underwear.