Coup d'etat is a French term meaning overthrow of the state. It is often shortened to simply coup.
Minister Jaro Essa attempted a coup d'etat on Bajor in 2370. In the wake of the coup, led by Jaro's terrorist front, the Alliance for Global Unity, Jake Sisko and Nog were evacuated from Deep Space 9 on different runabouts. However, although he couldn't pronounce the word quite right, Nog assured Jake that nothing would keep the best friends apart. (DS9: "The Circle")
- Nog: "If our fathers couldn't break us up, no stupid coupe day... coupe day..."
- Jake: "Coup d'etat. It's French."
- Nog: "Well, no stupid French thing will either."
In 2371, the Krajensky Changeling told Benjamin Sisko that the Tzenkethi autarch had been overthrown in a coup d'etat, although this was later proven to be a Dominion ruse to start another war between the Federation and the Tzenkethi. (DS9: "The Adversary")