era
Pronunciation: /ˈɪərə/
noun
- a long and distinct period of history: his death marked the end of an era leading photographers of the Victorian era
- a system of chronology dating from a particular event: the dawn of the Christian era
- Geology a major division of time that is a subdivision of an aeon and is itself subdivided into periods: the Mesozoic era
- archaic a date or event marking the beginning of a new and distinct period of time: the landing of this English governor was an era in their lives

Origin:
mid 17th century: from late Latin aera, denoting a number used as a basis of reckoning, an epoch from which time is reckoned, plural of aes, aer- 'money, counter'