[cladistics] In cladistics or phylogenetics, an outgroup is a (monophyletic) group of organisms that serve as a reference group when determining the evolutionary relationship among three or more monophyletic groups of organisms. The chosen outgroup is hypothesized to be closely related to the other groups but less closely related than any s...
a social group towards which one feels competition or opposition
Any group with which a person does not share membership.
In a cladistic analysis, any taxon used to help resolve the polarity of characters, and which is hypothesized to be less closely related to each of the taxa under consideration than any are to each other.
A group to which one does not belong.