def1.Girls in a friend group who act like they practically live together and cant ever be separated and have seen the worst of each other;since they arent actuly sisters they call themselfs shisters
def2.A veiwer of James Charles
a stupid thing many basic white girlssay. if you say "shister", you are basic, and trying desperately to be cool. shister is like the female version of bro, but more cringey.