An armistice is a formal agreement of warring parties to stop fighting. It is not necessarily the end of a war, as it may constitute only a cessation of hostilities while an attempt is made to negotiate a lasting peace. It is derived from the Latin arma, meaning "arms" (as in weapons) and -stitium, meaning "a stopping".

The United Nations Security Council often imposes, or tries to impose, cease-fire resolutions on parties in modern conflicts. Armistices are always negotiated between the parties themselves and are thus generally seen as more binding than non-mandatory UN cease-fire resolutions in modern international law.

An armistice is a modus vivendi and is not the same as a peace treaty, which may take months or even years to agree on. The 1953 Korean War Armistice Agreement is a major example of an armistice which has not been followed by a peace treaty. An armistice is also different from a truce or ceasefire, which refer to a temporary cessation of hostilities for an agreed limited time or within a limited area. A truce may be needed in order to negotiate an armistice.