Bishōnen (美少年. literally, "beautiful boy") is a specific Japanese aesthetic concept of the ideally beautiful young man. The prefix bi_ (美) specifically refers to feminine beauty (bijin, lit. "beautiful person", refers to a beautiful woman.) The bishōnen is typically quite slender and not very muscular, with a tapered chin, stylish hair, and an overall effeminate or androgynous appearance. The aesthetic of the bishōnen began as an ideal of a young homosexual lover, likely arising from the effeminate male actors who played female characters in Kabuki theater. It is perpetuated today in anime and manga, especially shojo (girl) anime, shonen_ai, and yaoi.
Some western anime and manga fans use the term (incorrectly) to refer to any handsome male character regardless of age, rather than teenage or younger, often shortening it to 'bishie.' It is occasionally even used to describe some androgynous female characters (such as Lady Oscar in Rose of Versailles, as well as Karou no Kimi and Hana no Saint Juste in Oniisama E)
Alternative spellings are bishonen and bishounen. Occasionally biseinen (lit. "beautiful young man") is seen as a synonym. However, biseinen also usually refers to a handsome man older than a bishounen, since the age range of a bishounen tends to be from 14-19, while a biseinen is often 20+. A handsome male below 14 is sometimes referred to as a bishota, although this character type is often seen in male child pornography.
Bishounen (literally, "beautiful boy") refers to a specific Japanese aesthetic concept of the ideally beautiful young man. The prefix bi- specifically refers to feminine beauty (bijin, lit.
The bishounen is typically quite slender and not very muscular, with a tapered chin and effeminate or androgynous appearance.
The aesthetic of the bishounen began as an ideal of a young homosexual lover.
Bishounen tend to have long eyes that appear to have possibly benefitted from selective use of eyeliner, instead of the cute 'round eyes' given to the standard males.
Generally, a bishounen that wears revealing clothing (generally meaning that his chest is revealed) is an evil bishounen.
Truly evil bishounen wear enormous shoulder-armor, sometimes extending the width of their shoulders to two or three times normal size, with a huge cape depending from the armor that hides their entire body.