Unchecked Aversion

Allowing an irrational aversion to affect ones understanding or treatment of a category of people. For any number of reasons, a person may develop an aversion against a concept, and thus against people associated with that concept. Such aversions might need to be kept in check, lest they bloom into outright bigotry... or even a phobia, in the clinical sense. (In Swedish: ohämmad aversion)

Stigmatization as a facet of categorism

Something is a facet of categorism when it on some level and based on a categorization of people is an expression of prejudice, bigotry, discrimination, or some combination thereof. When Unchecked Aversion is based on a categorization of people, it is a matter of bigotry combined with prejudice. Which is often fueled by and used to further fuel prejudice and/or discrimination.

Unchecked Aversion is bigotry: It is a matter of hostile emotions running amok.
Unchecked Aversion is prejudice: To indulge in hostile emotions is sometimes justified. Unchecked Aversion as a facet of categorism is when these emotions are dysfunctional by missing the justified target or by not being justified in the first place.
Unchecked Aversion can be fueled by discrimination: The "just world fallacy". The emotional need to perceive current practices, whatever those practices might be, as being "fair".
Unchecked Aversion can fuel other prejudice, bigotry and discrimination: As you indulge your contempt or hatred, anything can feel justified.

Interactions

This facet of categorism is an expression of bigotry, leading to prejudice and discrimination.

It is likely to intersect with facets such as:

Monolithization: When someone has something worthy of contempt, fear or hatred, it may be tempting to feel that way towards everyone who share the same skin color, gender or other such trait.
Othering: Distancing yourself from the ones you dislike.
Representation Bias: Letting the negative experiences grow into bigotry.
Scapegoating: When you have reason to despise something, it may feel good to blame it on a category of people.
Stigmatization: Pouring disgust over whatever group of people you have an emotional bias against.
Supremacism: Telling yourself that you are superior to the ones you dislike.

As well as with abstractions such as:

Categorization by emotional bias: Meeting someone nice from the targeted category could be a valuable lesson that the aversion is all in your own head and not something that everyone you target deserves... but it's easier to decide that this person doesn't really count.

Examples of applying this facet to a particular foci of categorism can include:

Sexism: Having been hurt before by men or women, one might be a bit reluctant to let someone new into one's heart. Which might spare oneself further heartache. However, nurturing this aversion too much may let it grow into outright bigotry against innocent people of the targeted gender.