The fulfillment of a flourishing, well-lived life — deeper than momentary pleasure..
The supreme human good — a life of flourishing in which one lives and acts well — and the central aim of Aristotelian ethics, understood as an objectively good life rather than a transient pleasant feeling. Often (misleadingly) translated “happiness.”
Differs sharply from happiness, contentment, or a pleasant mood: those denote a subjective feeling, while eudaimonia is an objective condition of a well-lived life that includes virtue (aretē), friends, and external goods — and can be affected by things one doesn't even know about. A philosophical concept, not a felt emotion; W. D. Ross suggested “well-being,” John Cooper “flourishing,” as better renderings.
eu “good, well” + daimon “spirit, indwelling guiding spirit” = “the state of a good spirit.”
An abstract noun from eû (“good, well”) + daímōn (“spirit, deity”) — being watched over by, or in the state of, a benevolent guardian spirit, hence overtones of being “fortunate, blessed.”
Central to Aristotle's Nicomachean Ethics, where everyone agrees eudaimonia is the highest good but disagrees on what it is; the Stoics held virtue sufficient for it, Epicurus made virtue instrumental to a distress-free life. Revived in 20th-century virtue ethics (Anscombe) and positive psychology (“eudaimonic well-being”).
The “happiness” translation is widely flagged as a distortion — happiness connotes a subjective feeling, whereas eudaimonia is an objective, encompassing condition of faring well. Scholars recommend “flourishing” or “well-being,” or leaving it untranslated.