From The Art and Popular Culture Encyclopedia
Sui generis is a Latin expression, literally meaning of its own kind/genus or unique in its characteristics. The expression was created to indicate an idea, an entity or a reality that cannot be included in a wider concept. In the structure "genus → species" a species that heads its own genus is sui generis. The word is pronounced SOO-eye jen-ER-ihs. A modern day equivalent is the phrase genre-defying.