era
Cross references:
1. period
era \'i(*)r-*, 'er-*, 'e--r*\ n [LL aera, fr. L, counters, pl. of aer-, aes
copper, money -] more at ORE 1: a system of chronological notation computed
from a given date as basis 2a: a fixed point in time for which a series of
years is reckoned 2b: a memorable or important date or event; esp : one
that begins a new period in the history of a person or thing 3a: a period
set off or typified by some prominent figure or characteristic feature 3b:
a stage in the development of a person or thing; specif : one o f the five
major divisions of geologic time {Paleozoic ~}