"In sociology and social psychology, an ingroup is a social group to which a person psychologically identifies as being a member. By contrast, an outgroup is a social group with which an individual does not identify."
"A social identity is the portion of an individual's self-concept derived from perceived membership in a relevant social group.[1] As originally formulated by Henri Tajfel and John Turner in the 1970s and the 1980s,[2] social identity theory introduced the concept of a social identity as a way in which to explain intergroup behaviour.[3][4][5]"
Still, individuals do change their ingroup membership and can remain as intolerant to then fully new outgroup. It would be good to have a name for this phenomenon: being intolerant to whatever person's current outgroup is. And there is one, which happens to have more uses than only this:
"The word is often used to refer to preconceived, usually unfavorable, judgments toward people or a person because of gender, political opinion, social class, age, disability, religion, sexuality, race/ethnicity, language, nationality, or other personal characteristics. In this case, it refers to a positive or negative evaluation of another person based on their perceived group membership.[1]"
https://en.wikipedia.org/wiki/Ingroups_and_outgroups
"In sociology and social psychology, an ingroup is a social group to which a person psychologically identifies as being a member. By contrast, an outgroup is a social group with which an individual does not identify."
https://en.wikipedia.org/wiki/Social_identity_theory
"A social identity is the portion of an individual's self-concept derived from perceived membership in a relevant social group.[1] As originally formulated by Henri Tajfel and John Turner in the 1970s and the 1980s,[2] social identity theory introduced the concept of a social identity as a way in which to explain intergroup behaviour.[3][4][5]"
Still, individuals do change their ingroup membership and can remain as intolerant to then fully new outgroup. It would be good to have a name for this phenomenon: being intolerant to whatever person's current outgroup is. And there is one, which happens to have more uses than only this:
https://en.wikipedia.org/wiki/Prejudice
"The word is often used to refer to preconceived, usually unfavorable, judgments toward people or a person because of gender, political opinion, social class, age, disability, religion, sexuality, race/ethnicity, language, nationality, or other personal characteristics. In this case, it refers to a positive or negative evaluation of another person based on their perceived group membership.[1]"