In scientific classification used in biology, the order is a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family. An immediately higher rank, superorder, may be added directly above order, while suborder would be a lower rank. a taxonomic unit, a taxon, in that rank. In that case the plural is orders (Latin ordines).