Seditiousness refers to behavior that incites rebellion against lawful authority. Some synonyms for seditiousness include insurrection, treason, disloyalty, subversion, and sedition. Insurrection suggests an uprising against established authority, while treason refers to a betrayal of one's country or loyalty. Disloyalty indicates a lack of faith or allegiance to an established authority. Subversion refers to an attempt to undermine or overthrow an established system or institution. Sedition suggests behavior that incites rebellion or resistance against lawful authority. Ultimately, all of these terms imply a challenge to established authority, whether through overt or covert means.