Serenity
Part of speech: noun
Definition: The state of being serene; calmness; peacefulness. A lack of agitation or disturbance. A title given to a reigning prince or similar dignitary.
Example sentence: I have learned to like myself for the first time and to have some serenity.
Tranquillity
Part of speech: noun
Definition: the state of being tranquilthe absence of disturbance; peacefulnessthe absence of stress; serenitythe quality of calm such as that experienced in places with mainly natural features and activities, free from disturbance from manmade ones.
Example sentence: Fishing gives me peace, tranquillity. And also, as a forward player, it helps me with my eyes.