The realization of potential; the supposed vital force that guides development and fulfillment; the condition of something whose essence is fully realized.
From Greek 'entelecheia' — 'en' (in) + 'telos' (end/perfection) + 'echein' (to have). Aristotle's concept: the acorn contains the oak's entelechy — the invisible blueprint of everything it's meant to become.
Try Another Word