[Henderson's] n. in sexually reproducing organ­isms, a group of interbreeding individuals not normally able to interbreed with other such groups. A species is given two names in binomial nomenclature (e.g. Homo sapiens), the generic name and specific epithet (italicized in the scientific liter­ature), similar and related species being grouped into genera. Species can be sub­divided into subspecies, geographic races, and varieties.