A cease fire or truce is an official halt of hostilities during a time of war or other types of conflict.
In 2152, Andorian commander Shran requested the presence of Enterprise captain Jonathan Archer to negotiate a cease fire between the Andorians and the Vulcans on the planet known as both Paan Mokar and Weytahn. (ENT: "Cease Fire")
In 2369, Benjamin Sisko, Kira Nerys and Kai Opaka attempted to get the Ennis and the Nol-Ennis to call a cease fire, although the two groups had been fighting for so long neither took it seriously. (DS9: "Battle Lines")
Several weeks later, the cease fire was broken when Klingon troops invaded the Federation planet Ajilon Prime. Many people were killed during the period before the ceasefire was reinstated. The USS Farragut was destroyed near the Lembatta Cluster during the period. (DS9: "Nor the Battle to the Strong")