Meaning

noun a sudden and decisive change of government illegally or by force

noun a brilliant and notable success

originReborrowed in modern times from modern French coup (“blow, strike”), from Old French coup, colp, from Late Latin colpus, from Latin colaphus. Doublet of cope and colpus. The same Old French word had been borrowed into Middle English as coupe, caupe (with different pronunciation).

Etymology from Wiktionary, CC BY-SA 3.0