So important or significant that it marks a major division or turning point in history or someone's life.
From 'epoch' + '-al' (adjective-forming suffix). Derived from Greek 'epochē' (stopping point), the adjective form emerged in the 18th century to describe events of historical magnitude.
The invention of the printing press, the discovery of electricity, and the moon landing are 'epochal'—they're moments when the timeline of human history literally gets divided into 'before' and 'after.'
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