noun. Same as ataraxia.

noun. The freedom from mental disturbance; imperturbability, dogged indifference.

"This fear is one source of perturbation (tarakhê), and is a worse curse than physical pain itself; the absence of such fear is ataraxy, lack of perturbation, and ataraxy, together with freedom from physical pain, is one way of specifying the goal of life, for Epicurus."

accidia  acedia  aloofness  apathy  ataraxia