noun, plural: classes
(1) A group or set (of things or entities) with common characteristics, attributes, qualities or traits.
(2) A taxonomic group comprised of organisms that share a common attribute. It is further divided into one or more orders.
In biological classification of organisms, a class is a major taxonomic rank below the phylum (or division) and above the order. For example, class Mammalia belongs to phylum Chordata. Class Mammalia is comprised of various orders such as Chiroptera (bats), Primates (apes), Carnivora (dogs, cats, jaguar, bears, etc.), Cetacea (whales), Proboscidea (elephants), and many others.
See also: taxonomy