An agreement or a treaty to end hostilities. Freedom from quarrels and disagreement; harmonious relations: roommates living in peace with each other. Inner contentment; serenity: peace of mind. at peace In a state of tranquillity; serene: She is at peace with herself and her friends. keep To be silent. keep the peace To maintain or observe law and order: officers who were sworn to keep the peace. The absence of war or other hostilities. Public security and order: was arrested for disturbing the peace. Used as a greeting or farewell, and as a request for silence. at peace Free from strife: Everyone wants to live in a world at peace.