/
ˈɪərə/
n.
a long and distinct period of history.
▸Geology a major division of time that is a subdivision of an aeon and is itself subdivided into periods.
Etymology
C17: from late L. aera, denoting a number used as a basis of reckoning, an epoch from which time is reckoned, pl. of aes, aer- ‘money, counter’.
