anti-mainstream faction; fringe group; dissident group
Refers to a group or faction that opposes the dominant trend, ideology, or establishment within a larger organization, field, or society.
The anti-mainstream faction within the party strongly opposes the new policy.
He is known as a dissident in academic circles.
主流派 means 'mainstream faction' or 'establishment group', the direct opposite of 反主流派.
異端 means 'heresy' or 'heterodoxy' and often carries a stronger connotation of being outside accepted norms, while 反主流派 is more neutral and organizational.
Compound of 反 (anti-) + 主流 (mainstream) + 派 (faction, group).