Revolutionary defeatism is a term coined by Lenin that first appeared in his 1915 article The defeat of one’s own government in the imperialist war, while Russia was deep in the middle of the First World War.
According to Lenin, the definition of revolutionary defeatism can be summed up with the opening paragraph to his article: "During a reactionary war a revolutionary class cannot but desire the defeat of its government."
He further argues that the revolutionary class (the proletariat in the age of capitalism) should do everything in their power to bring about the defeat of their government during imperialist wars, so that a revolution can stem from that war.