peace 
(pēs)
(pēs)n.
1. The absence of war or other hostilities.
2. An agreement or a treaty to end hostilities: negotiated the peace.
3. Freedom from quarrels and disagreement; harmonious relations: roommates living in peace with each other.
4. Public security and order: was arrested for disturbing the peace.
5. Inner contentment; serenity: peace of mind.
interj.
Idioms: Used as a greeting, a farewell, or a request for silence.
at peace
1. In a state of tranquility; serene: She is at peace with herself and her friends.
2. Free from strife: Everyone wants to live in a world at peace.
keep/hold (one's) peace
To be silent.
keep the peace
To maintain or observe law and order: officers who were sworn to keep the peace.
peace out Slang
Used to express "goodbye."
[Middle English pes, from Old French pais, pes, from Latin pāx, pāc-; see PAX.]