Prefix used in loanwords and modern compounds to express opposition or being against something.
I installed anti-virus software on my computer.
He is looking for anti-aging cosmetics.
hater; anti-fan
Colloquial noun for a person who actively dislikes or criticizes a celebrity, work, or group.
That idol has a lot of haters.
He ended up becoming a hater of that actor.
Once you become famous, you're bound to attract haters.
アンチ refers to someone who dislikes and criticizes a celebrity or work, while ファン is a supporter who likes it, making the two opposite roles in online fandom culture.
Borrowed from English 'anti-'.
antifreeze
anti-doping
anti-hacking