High Quality Content by WIKIPEDIA articles! Unilateralism is any doctrine or agenda that supports one-sided action. Such action may be in disregard for other parties, or as an expression of a commitment toward a direction which other parties may find agreeable. Unilateralism is a neologism, (though already in common use) coined to be an antonym for multilateralism —the doctrine which asserts the benefits of participation from as many parties as possible.