Undertaken, decided, or performed by only one side, party, or country without the agreement or participation of others

Latin uni- (one) + lateralis (of the side); entered legal and diplomatic vocabulary in the 19th century to distinguish one-party acts from bilateral or multilateral agreements

One-sided Independent Solo Uncoordinated
Bilateral Multilateral Consensual Collaborative
"India's unilateral decision to revoke Jammu and Kashmir's special status under Article 370 was welcomed domestically but drew sharp criticism from Pakistan and raised concerns at the UN Human Rights Council."

Essential for GS-2 (IR, polity) answers. Use whenever one country or party acts without multilateral consent — US withdrawal from Paris Agreement, India's surgical strikes, China's unilateral declaration of an Air Defence Identification Zone. Contrasting unilateral with multilateral approaches is a classic UPSC framework for evaluating international decisions.

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