noun, plural: subclasses
The hierarchy of biological classification has about eight major taxonomic ranks. The eight major taxonomic ranks are as follows (in the descending order of size): life, domain, kingdom, phylum, class, order, family, genus, and species. In between these major ranks are minor ranks that may be indicated with prefixes. For instance, for the major taxonomic rank class, minor ranks may include superclass (meaning above), subclass (meaning under), infraclass (meaning below), and parvclass (meaning small or unimportant).
A subclass is a minor taxonomic rank that is below a class and above an order. For instance, class Mammalia may be further subdivided into subclasses. The class Mammalia is comprised of vertebrates that are characterized by being endothermic amniotes. They may be further classified into subclasses Prototheria and Theriiformes. The Prototheria is a subclass comprised of echidnas and the platypuses. The subclass Theriiformes includes live-bearing mammals such as the eutherians (placental mammals) and the metatherians (marsupials).
Word origin: sub- (below) + class