Sui generis (English pronunciation (IPA): /ˌsuːiˈʒɛnərɪs/, roughly "SOO-ee JEN-er-ihs", Latin pronunciation: /ˌsuːiˈgeneris/) is a Neo-Latin expression, literally meaning of its own kind/genus or unique in its characteristics. The expression was effectively created by scholastic philosophy 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. This does not, however, mean that all genera with only a single member are composed of sui generis species. It is only if the genus was specifically created to refer to that one species, with no other known examples, that the species is sui generis. If the species is alone merely due to extinction, as in the case of the Homo genus, the surviving species is not sui generis, because other members of the genus are known, even if they are not currently alive.