subclass

[suhb-klas, -klahs] /ˈsʌbˌklæs, -ˌklɑs/
noun
1.
a primary division of a class.
2.
a subordinate class, especially one of persons who lack the rights and privileges of the primary class:
a subclass of alien workers.
3.
Biology. a category of related orders within a class.
verb (used with object)
4.
to place in a subclass.
Origin
1810-20; sub- + class
British Dictionary definitions for subclasses

subclass

/ˈsʌbˌklɑːs/
noun
1.
a principal subdivision of a class
2.
(biology) a taxonomic group that is a subdivision of a class
3.
(maths) another name for subset (sense 1)
verb
4.
(transitive) to assign to a subclass
subclasses in Medicine

subclass sub·class (sŭb'klās')
n.
A taxonomic category of ranking between a class and an order.

subclasses in Science
subclass
  (sŭb'klās')   
A taxonomic category of related organisms ranking below a class and containing one or more orders.