epoch
/ˈiːpɒk/noun
1- a period of time in history or a person's life, typically one marked by notable events or particular characteristics时期; 时代：
the Victorian epoch.
维多利亚时代。
1.1
- the beginning of a distinctive period in the history of someone or something新纪元, 新时期。
1.2
- Geology a division of time that is a subdivision of a period and is itself subdivided into ages, corresponding to a series in chronostratigraphy【地质】世：
the Pliocene epoch.
上新世。
1.3
- Astronomy an arbitrarily fixed date relative to which planetary or stellar measurements are expressed【天文】历元。
词源
early 17th cent. （in the Latin form epocha ; originally in the general sense of a date from which succeeding years are numbered）： from modern Latin epocha, from Greek epokhē'stoppage, fixed point of time', from epekhein 'stop, take up a position', from epi 'upon, near to' + ekhein 'stay, be in a certain state'.