1. a long and distinct period of history with a particular feature or characteristic: "his death marked the end of an era"
▪ a system of chronology dating from a particular noteworthy event: "the dawn of the Christian era"
▪ a major division of time that is a subdivision of an eon and is itself subdivided into periods: "the Mesozoic era"
▪ a date or event marking the beginning of a new and distinct period of time.
Word Originmid 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’.
