In biological terms, a genus is a category or a classification that ranks under a family and above a species which usually consists of a collection of species that portray resembling characteristics. In taxonomic categorisation the name of the genus is used either on its own or succeeded by a Latin epithet, to make the name of a species. For example, ‘Homo Sapiens’, is the name of the human species. The genus here is ‘homo’. A genus may also denote plant species exhibiting similar features. For example, all roses are collectively a part of the genus Rosa

In logic terms, it means a class of items segregated into secondary species that have particular common characteristics.

It can simply be used to describe a class, or a group that shares a common trait.