a sudden and decisive change of government illegally or by force
"The army staged a coup to overthrow the elected president in a bloodless takeover."
a brilliant and notable success
"The team's unexpected victory was nothing short of a coup in their first season."
A quick, brilliant, and highly successful act.
"The team's sudden counterattack was a coup that secured victory in the final minutes of the game."
In plain English: A coup is when a small group of people secretly takes control of a government by force without waiting for an election.
"The sports team celebrated their sudden victory with chants after scoring three goals in just two minutes, which was considered a real coup for such an underdog squad."
Usage: This term refers specifically to a sudden political overthrow of a government by force or fraud; using it to describe any minor success or clever trick is incorrect. Do not confuse the spelling with "coop," which means an enclosure for poultry.
To make a coup.
"The general attempted to seize power by making a coup against the government."
The modern English word "coup" was reborrowed in the 19th century directly from French to mean a sudden blow or stroke. It originally entered English much earlier with similar meanings but fell out of use before being reintroduced by writers like Charles Dickens and Mark Twain.