| subclass | (n) (biology) a taxonomic category below a class and above an order |
| Acnidosporidia | (n) a subclass of Sporozoa, Syn. subclass Acnidosporidia |
| Actinopoda | (n) heliozoans; radiolarians, Syn. subclass Actinopoda |
| Alismatidae | (n) one of four subclasses or superorders of Monocotyledones; comprises about 500 species in 14 families of aquatic and semiaquatic herbs, Syn. subclass Alismatidae |
| Amphineura | (n) a class of Gastropoda, Syn. subclass Amphineura |
| Anapsida | (n) oldest known reptiles; turtles and extinct Permian forms, Syn. subclass Anapsida |
| Archaeornithes | (n) primitive reptile-like fossil birds of the Jurassic or early Cretaceous, Syn. subclass Archaeornithes |
| Archosauria | (n) a large subclass of diapsid reptiles including: crocodiles; alligators; dinosaurs; pterosaurs; plesiosaurs; ichthyosaurs; thecodonts, Syn. subclass Archosauria |
| Arecidae | (n) one of four subclasses or superorder of Monocotyledones; comprises about 6400 species in 5 families of trees and shrubs and terrestrial herbs and a few free-floating aquatics including: Palmae; Araceae; Pandanaceae and Lemnaceae, Syn. subclass Arecidae |
| Asteridae | (n) a group of mostly sympetalous herbs and some trees and shrubs mostly with 2 fused carpels; contains 43 families including Campanulales; Solanaceae; Scrophulariaceae; Labiatae; Verbenaceae; Rubiaceae; Compositae; sometimes classified as a superorder, Syn. subclass Asteridae |
| Branchiopoda | (n) primitive aquatic mainly freshwater crustaceans: fairy shrimps; brine shrimps; tadpole shrimps; can shrimps; water fleas, Syn. subclass Branchiopoda |
| Caryophyllidae | (n) a group of families of mostly flowers having basal or central placentation and trinucleate pollen (binucleate pollen is commoner in flowering plants); contains 14 families including: Caryophyllaceae (carnations and pinks); Aizoaceae; Amaranthaceae; Batidaceae; Chenopodiaceae; Cactaceae (order Opuntiales); Nyctaginaceae; Phytolaccaceae; corresponds approximately to order Caryophyllales; sometimes classified as a superorder, Syn. subclass Caryophyllidae |
| Cirripedia | (n) barnacles, Syn. subclass Cirripedia |
| Cnidosporidia | (n) single-host parasites of lower vertebrates and invertebrates, Syn. subclass Cnidosporidia |
| Commelinidae | (n) one of four subclasses or superorders of Monocotyledones; comprises about 19, 000 species in 25 families of mostly terrestrial herbs especially of moist places including: Cyperaceae; Gramineae; Bromeliaceae; and Zingiberaceae, Syn. subclass Commelinidae |
| Copepoda | (n) minute planktonic or parasitic crustaceans, Syn. subclass Copepoda |
| Crossopterygii | (n) fishes having paired fins resembling limbs and regarded as ancestral to amphibians, Syn. subclass Crossopterygii |
| Diapsida | (n) used in former classifications to include all living reptiles except turtles; superseded by the two subclasses Lepidosauria and Archosauria, Syn. subclass Diapsida |
| Dibranchiata | (n) comprising all living cephalopods except the family Nautilidae: the orders Octopoda (octopuses) and Decapoda (squids and cuttlefish), Syn. Dibranchia, subclass Dibranchiata, subclass Dibranchia |
| Dilleniidae | (n) a group of families of more or less advanced trees and shrubs and herbs having either polypetalous or gamopetalous corollas and often with ovules attached to the walls of the ovary; contains 69 families including Ericaceae and Cruciferae and Malvaceae; sometimes classified as a superorder, Syn. subclass Dilleniidae |
| Dipnoi | (n) bony fishes of the southern hemisphere that breathe by a modified air bladder as well as gills; sometimes classified as an order of Crossopterygii, Syn. subclass Dipnoi |
| Discomycetes | (n) a large and taxonomically difficult group of Ascomycetes in which the fleshy fruiting body is disklike or cup-shaped, Syn. subclass Discomycetes |
| Elasmobranchii | (n) sharks; rays; dogfishes; skates, Syn. subclass Selachii, Selachii, subclass Elasmobranchii |
| Entomostraca | (n) in some older classifications includes the Branchiopoda and Copepoda and Ostracoda and Cirripedia; no longer in technical use, Syn. subclass Entomostraca |
| Euascomycetes | (n) category not used in many classification systems, Syn. subclass Euascomycetes |
| Euryalida | (n) basket stars, Syn. subclass Euryalida |
| Eutheria | (n) all mammals except monotremes and marsupials, Syn. subclass Eutheria |
| Exopterygota | (n) subclass of insects characterized by gradual and usually incomplete metamorphosis, Syn. subclass Exopterygota, Hemimetabola |
| Hamamelidae | (n) a group of chiefly woody plants considered among the most primitive of angiosperms; perianth poorly developed or lacking; flowers often unisexual and often in catkins and often wind pollinated; contains 23 families including the Betulaceae and Fagaceae (includes the Amentiferae); sometimes classified as a superorder, Syn. subclass Hamamelidae |
| Heterobasidiomycetes | (n) category used in some classification systems for various basidiomycetous fungi including rusts and smuts, Syn. subclass Heterobasidiomycetes |
| Holocephali | (n) chimaeras and extinct forms, Syn. subclass Holocephali |
| Homobasidiomycetes | (n) category used in some classification systems for various basidiomycetous fungi including e.g. mushrooms and puffballs which are usually placed in the classes Gasteromycetes and Hymenomycetes, Syn. subclass Homobasidiomycetes |
| Infusoria | (n) in some recent classifications, coextensive with the Ciliata: minute organisms found in decomposing infusions of organic matter, Syn. subclass Infusoria |
| Lepidosauria | (n) diapsid reptiles: lizards; snakes; tuataras, Syn. subclass Lepidosauria |
| Liliidae | (n) one of four subclasses or superorders of Monocotyledones; comprises 17 families including: Liliaceae; Alliaceae; Amaryllidaceae; Iridaceae; Orchidaceae; Trilliaceae, Syn. subclass Liliidae |
| Magnoliidae | (n) a group of families of trees and shrubs and herbs having well-developed perianths and apocarpous ovaries and generally regarded as the most primitive extant flowering plants; contains 36 families including Magnoliaceae and Ranunculaceae; sometimes classified as a superorder, Syn. subclass Magnoliidae, ranalian complex |
| Malacostraca | (n) largest subclass of Crustacea including most of the well-known marine, freshwater, and terrestrial crustaceans: crabs; lobsters; shrimps; sow bugs; beach flies, Syn. subclass Malacostraca |
| Metatheria | (n) pouched animals, Syn. subclass Metatheria |
| Ophiurida | (n) brittle stars, Syn. subclass Ophiurida |
| Opisthobranchia | (n) gastropods having the gills when present posterior to the heart and having no operculum: includes sea slugs; sea butterflies; sea hares, Syn. subclass Opisthobranchia |
| Ostracoda | (n) seed shrimps, Syn. subclass Ostracoda |
| Pantotheria | (n) generalized extinct mammals widespread during the Jurassic; commonly conceded to be ancestral to marsupial and placental mammals, Syn. subclass Pantotheria |
| Phytomastigina | (n) plantlike flagellates containing chlorophyll; often considered unicellular algae, Syn. subclass Phytomastigina |
| Prototheria | (n) echidnas; platypus, Syn. subclass Prototheria |
| Rhizopoda | (n) creeping protozoans: amoebas and foraminifers, Syn. subclass Rhizopoda |
| Rosidae | (n) a group of trees and shrubs and herbs mostly with polypetalous flowers; contains 108 families including Rosaceae; Crassulaceae; Myrtaceae; Melastomaceae; Euphorbiaceae; Umbelliferae, Syn. subclass Rosidae |
| Synapsida | (n) extinct reptiles of the Permian to Jurassic considered ancestral to mammals, Syn. subclass Synapsida |
| Teleostei | (n) large diverse group of bony fishes; includes most living species, Syn. subclass Teleostei |
| Telosporidia | (n) parasitic sporozoans that form spores containing one or more infective sporozoites, Syn. subclass Telosporidia |
| Zoomastigina | (n) in some classifications considered a phylum of the kingdom Protista; holozoic or saprozoic flagellates, Syn. subclass Zoomastigina |
