Serenity

Part of speech: noun (n.)

1. The quality or state of being serene; clearness and calmness; quietness; stillness; peace. A general peace and serenity newly succeeded a general trouble. Sir W. Temple.

2. Calmness of mind; eveness of temper; undisturbed state; coolness; composure. I can not see how any men should ever transgress those moral rules with confidence and serenity. Locke.