Ataraxia is a blissful, peaceful state of mind. Many people who meditate hope to achieve a state of ataraxia.
If you tend to get flustered, you're probably envious of your calm, serene friend's ataraxia — it might seem like she never seems to worry about anything. This word is sometimes written as ataraxy in English, from the Greek root ataraxia, literally "impassiveness," from a-, "not," and tarassein, "to disturb or confuse." In ancient Greece, the Epicureans most famously sought the state of ataraxia, which they considered to be true happiness.