For other uses, see Sui Generis (disambiguation). Sui generis (/ˌsuːaɪ ˈdʒɛnərɪs/; Latin: [ˈsʊ.iː ˈɡɛnɛrɪs]) is a Latin phrase, meaning of its (his, her, or their) own kind; in a class by itself; unique. The term is widely used to refer to more esoteric entities in a number of disciplines, including. philosophy, to indicate an idea, an entity, or a reality which cannot be reduced to a lower concept or included in a higher concept;