The act of overthrowing something or someone.(noun)
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Use "overthrowal" in a sentence
"Responsible government within their own Colony would lead to the "overthrowal" of that Empire, and the reduction of Britain to a "second-rate Power.""
"And not so much an overthrowal as an infiltration and reform."
"What there was most distressing to him was the overthrowal of the Church, and he did not hesitate, in very striking fashion, to connect revolutionary opinion with infidelity."