species
,
n
8. a. A class composed of individuals having some common
qualities or characteristics, freq. as a subdivision of a larger
class or genus.
10.
Zool
. and
Bot
. A group or class of animals
or plants (usually constituting a subdivision of a genus) having
certain common and permanent characteristics which clearly
distinguish it from other groups. The exact definition of a species,
and the criteria by which species are to be distinguished (esp. in
relation to genera or varieties), have been the subject of much
discussion.
-- Oxford English Dictionary,
2nd edn