Two definitions seen:
1) An anti-shipper or anti-proshipper. Proshippers are those who claim to "separate fiction from reality" and ship whatever their (sick) hearts desire. These ships may include incest, pedophilia, or abusive/toxic relationships. Many pro-shippers are "kodocons", a Japanese term for
one who is sexually attracted to child characters. Most commonly, lolicons
will be a *big* fan of Kanna Kamui from Miss Kobayashi's Dragon Maid, a dragon who's human form is that of a first grader. Antis are against almost everything proshippers stand for, and are largely victims of the depicted crimes that proshippers adore. Some can be respectful, many making accounts to just poke
fun at their pro counterparts, but others
will go to extreme lengths to harm them. No matter what a person does, it is unreasonable to make
fun of their trauma, or expose their private personal information on the
Internet. Underage proshippers are mostly victims of grooming or believe the content they consume is a good, healthy coping mechanism. I cannot stress this enough, IT IS NOT. PROSHIPPING AND "PROBLEMATIC" CONTENT IS NOT A COPING MECHANISM, GO TO THERAPY (if you can access/afford it). Protect
real children, and protect
children's media and spaces.
and 2) A person who is largely not a fan of a certain musical group, singer/musician, actor, or other
real-person content medium. This term is largely used in K-Pop online circles.