Peace has a number of synonyms, which all have slightly different shades of meaning:
Serenity
The feeling of contentment and being completely full with no need for further additions to the self; a feeing of satisfaction, of wholeness of the self.
Calmness
There are no disturbances or waves in the mind, like a pool of water that is clear and still with not even a ripple to disturb it.
Tranquility
Tranquility is the state of harmony in nature and in ourselves that keeps everything in balance naturally.
Quietness
In this state, there are no sounds of uncontrolled thoughts jumping around like a monkey in the mind; our thoughts become essenceful, returning to the point, with no expansion; it is an economy of thinking that creates quietness.
Stillness
There is no movement of thoughts. I remain absorbed in one thought and, in the stillness of silence, I am at rest, with a feeling of complete detachment from everything.
Peace has the meaning of harmony, balance, order and freedom: when we are free from waste and negativity, then we exist fully serene, fully at peace with everything.
Peace is my original energy and treasure and with the practice of meditation I step inside and experience it.
~ Brahma Kumaris, Mt Abu.