epoch
n. countablen. a long period of time in history that is marked by important events or changes. It can also refer to the exact starting point of a new era.
n. a distinct period in history or a person's life, typically marked by notable events or particular characteristics. In technical contexts, it refers to a fixed point in time used as a reference for calculating dates or astronomical coordinates.
The invention of the steam engine marked a new epoch in history.
Geologists study different layers of rock to determine when one epoch ended and another began.
The fall of the Berlin Wall is often cited as the event that closed one political epoch and inaugurated a period of rapid globalization.
From Medieval Latin epocha, from Ancient Greek ἐποχή (epokhḗ, “a check, cessation, stop, pause, epoch of a star, i.e., the point at which it seems to halt after reaching the highest, and generally the place of a star; hence, a historical epoch”), from ἐπέχω (epékhō, “I hold in, check”), from ἐπι- (epi-, “upon”) + ἔχω (ékhō, “I have, hold”). Doublet of epoche.
Often used with the verb 'mark' or 'herald' to indicate the beginning of a significant historical shift.