secessionism

This term describes the ideological drive or organized effort to break away from a sovereign state. It carries a heavy political weight, often associated with nationalism, ethnic conflict, or systemic grievances. While secession is the act of leaving, secessionism is the belief system or the movement that justifies and promotes that act.

As an abstract noun representing a political philosophy or a collective movement, it is treated as an uncountable mass noun. It does not typically take a plural form in standard usage, as it refers to the general concept of advocacy rather than individual instances of withdrawal.