Autonomism refers to the belief in or advocacy for autonomy (self-government, independence from external control), often in political, regional, philosophical, or social contexts (e.g., autonomist movements in radical left politics, regional autonomy demands, or philosophical emphasis on self-determination).

There isn't a single exact one-word synonym that perfectly replaces "autonomism" in all uses, but here are the closest synonyms, near-synonyms, and related terms depending on context:

General / Common Synonyms (emphasizing the principle or state)

• Autonomy itself (the core concept)
• Self-determination
• Independence
• Self-government / self-rule
• Sovereignty
• Self-reliance
• Autarchy (self-rule or economic/political independence)

In Political / Ideological Contexts (e.g., autonomist movements, regional or radical politics)

• Separatism (when focused on breaking away for autonomy)
• Decentralism / decentralization (advocacy for distributed/self-managed power)
• Regionalism (regional self-governance)
• Independentism / independentist ideology
• Libertarianism (in some overlapping radical strains emphasizing individual/group autonomy)

Related or Associated Terms

• Anarchism (especially strains like autonomist anarchism or post-anarchism)
• Radical autonomy (sometimes used directly in theory)
• Pro-autonomy stance / movement

If you're referring to a specific type (e.g., Italian Autonomism / Operaismo, Basque/Catalan regional autonomism, or philosophical autonomy), feel free to clarify for more precise alternatives!