peace
-noun
1. the normal, nonwarring condition of a nation, group of nations or world.
2. (often cap.) an agreement or treaty between warring or antagonistic nations, groups, etc., to end hostilities and abstain from further fighting or antagonism
3. a state of mutual harmony between people or groups, especially in personal relation: try to live in peace with your neighbors.
4. cessation of or freedom from any strife or dissension.
5. a state of tranquillity or serenity.

-Idioms
at peace,
a. in a state or relationship of nonbelligerence or concord ; not at war :)
b. untroubled ; tranquil ; content :)