Sui generis

Sui generis (/ˌsuːi ˈdʒɛnərɪs/ SOO-ee JEN-ər-iss,^[1] Classical Latin: [ˈsʊ.iː ˈɡɛnɛrɪs]) is a Latin phrase that means 'of its/their own kind' or 'in a class by itself', therefore 'unique'.^[2]

Several disciplines use the term to refer to unique entities. These include:

Biology, for species that do not fit into a genus that includes other species^[3] (its own genus)
Creative arts, for artistic works that go beyond conventional genre boundaries (its own genre)
Law, when a special and unique interpretation of a case or authority is necessary (its own special case)
- Intellectual property rights, for types of works not falling under general copyright law but protected through separate statutes
Philosophy, to indicate an idea, an entity, or a reality that cannot be reduced to a lower concept or included in a higher concept (its own category)

^ "sui generis". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
^ Mawson, C. O. Sylvester (1975). "sui generis". Dictionary of Foreign Terms (2 ed.). New York: Thomas Y. Crowell Company. p. 328. ISBN 0-690-00171-1.
^ Bentham, George (1880). "Notes on Euphorbiaceæ". Journal of the Linnean Society, Botany. 17: 225 – via Google.