IPA: /ˈaʊtɡruːp/
KK: /ˈaʊtˌɡruːp/
A group of individuals or species that is not part of the main group being studied or considered, often used in scientific contexts to provide a comparison.
In the study of evolutionary relationships, researchers often include an outgroup to help clarify the characteristics of the ingroup.
Outgroup → It is formed from "out-" (meaning outside) and "group" (from Old French *groupe*, meaning a collection of individuals). The word "outgroup" refers to a group of individuals that is considered to be outside of a particular social group or community.
Think of 'outside' ('out-') and a 'collection of individuals' ('group') to remember that an outgroup is a group that is outside of your own social circle.