This page contains information regarding Star Trek: Discovery, and thus may contain spoilers.
An armistice was a formal agreement for the cessation of hostilities between two warring parties, prior to a formal peace treaty.
In 2367, an armistice was arranged between the Federation and the Cardassian Union. The Federation negotiator was Captain Edward Jellico. One of the terms of the armistice was that the Cardassians relinquished their claims to territories bordering their space. The final status of those territories was discussed in the negotiations for the Federation-Cardassian Treaty. (TNG: "Chain of Command, Part I")
That same year, there were armistice talks between Bajor and the Cardassian Union. Issues discussed in the talks included the lawful status of property seized by the Cardassians during the Occupation of Bajor and payment of reparations to Bajor. (DS9: "Life Support")