The term refers to lesbians, usually young ones. The term became
popular in Japan during the 70's and 80's due to a 70's Japanese magazine that called lesbians “the
lily tribe” causing the
lily flower to be associated with lesbianism.
During the early 2000's when anime and japanese culture became more accessible, the term begun to be used in other countries, but to this day, it is still used majorly in Japan.