stem
The stock of a family; a race or generation of progenitors.
Other meanings
A branch of a family.
A branch, or group of branches, located outside a family or other cladistic group, but which is more closely related to that group than to any other taxon of the same rank.
Word history
From Old English "stemn".
Where this comes from
This definition is adapted from “stem” on Wiktionary, by its contributors, published under CC BY-SA 4.0. This page is published under the same licence.