- In biology, genus is a taxonomic category
ranking below family and above species.
A genus is a group of closely related biological species with common
characteristics; for example the genus Canis includes the dog,
wolf, and jackal. Genus names are printed in italic with a capital letter;
for example, modern humans belong to the genus Homo. Plural:
- In topology,
genus, roughly speaking, is the number of holes in
a surface. Spheres, bowling balls and
wine glasses have a genus of 0 and can be represented by quadratic equations.
Bagels, inner tubes, and teacups have a genus of 1 and can be described
by cubic equations. Humans are more
difficult to specify. However, you will certainly increase your genus
by one if you have your ear pierced! Different definitions of genus
apply to other types of mathematical object such as a curve,
a knot, or a set.