Definition of "ataraxia"

And what happineſs is there in a ſtorm of paſſions? On this account the Scepticks affected an indifferent æquipondious neutrality as the only means to their Ataraxia, and freedom from paßionate diſturbances.

1665, Joseph Glanvill, chapter XXVII, in Scepsis Scientifica: Or, Confest Ignorance, the Way to Science; in an Essay of the Vanity of Dogmatizing, and Confident Opinion with a Reply to the Exceptions of the Learned Thomas Albius‎, London: E. Cotes, page 168

O, for that apathy of soul, that sweet ataraxia, of which I have heard, which forbids alike the approaches of pleasure and pain, hope and despair!

1838, Piomingo, John Robinson, The Savage‎, 2nd edition, Philadelphia: J. Ferral, page 194

That terrible Latin poet Lucretius, whose apparent serenity and Epicurean ataraxia conceal so much despair, said that piety consists in the power to contemplate all things with a serene soul—pacata posse mente omnia tueri.

1921, J.E. Crawford Flitch, transl., The Tragic Sense Of Life‎, translation of Del sentimiento trágico de la vida by Miguel de Unamuno

[…] he was an Epicurean not in the commonly misunderstood sense, as a seeker after luxury, but in the true meaning, as a pursuer of what the Greeks call ataraxia, or freedom from disturbance.

2006, Robert Harris, Imperium‎, London: Arrow Books, Part 2, Chapter 15, p. 400