Wiktionary
n. A Japanese music movement which emerged in the 1980s, characterized by eccentric, flamboyant looks and sometimes an androgynous appearance.
Wikipedia
is a movement among Japanese musicians, that is characterized by the use of varying levels of make-up, elaborate hair styles and flamboyant costumes, often, but not always, coupled with androgynous aesthetics.
Some Western sources think that visual kei refers to a music genre, with its sound usually related to glam rock, punk rock and heavy metal. However, visual kei acts play various genres, including those considered by some as unrelated to rock such as electronic, pop, etc. Other sources, including members of the movement themselves, state that it is not a music genre and that the fashion and participation in the related subculture is what exemplifies the use of the term.