Genus (noun, “GEE-nus,” plural, Genera, “GEN-er-ah”)
This is a word used in taxonomy for a group of closely related species. Taxonomy is the study of how organisms relate to each other. Genus is a very close relation — the species share a common ancestor that is relatively recent. Over time, groups of organisms in the genus adapted to slightly different ways of life. They formed different species.
For example, the genus Panthera is a group of closely related big cats. Lions, tigers, leopards, jaguars and snow leopards are all members of genus Panthera. They are not as closely related to smaller cats such as the jungle cat, sand cat and domestic cat. Those cats are in genus Felis. But they’re all cats. Both genera are in the family Felidae.
The genus is the first part of the two-part species naming system called “binomial nomenclature.” This is a formal system to name living things. Sometimes scientists call these names an organism’s “scientific name” or “Latin name.” Each two-part name includes the genus and the species. For example, humans aren’t just sapiens — that’s our species. Our full scientific name is Homo sapiens, which includes our genus Homo.