Subversive
/səbˈvɜr.sɪv/ adjective mediumSeeking to undermine or overthrow an established system, government, or set of ideas.
The pamphlet was considered subversive because it openly questioned the ruling party's authority.
Memory Trick
Sub- (under) plus vert (turn) — subversive literally means 'turning things under,' flipping the established order from below.