e·ra [ rə, érrə ]
noun
1. time distinctive period of history: a period of time made distinctive by a significant development, feature, event, or personality
during the postwar era
2. time period with own chronological system: a time period within which years are consecutively numbered from a particular significant event that provides its starting point
the Christian era
3. prehistory division of Earth’s history: a division of geologic time composed of several periods
4. time date that begins period: a significant date or event that is regarded as the beginning of a new period of time
The agreement marked an era in U.S.-Soviet relations.
[Mid-17th century. From late Latin aera “number used as a basis for counting.”]
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exo-
prefix
outside, external
exothermic
[From Greek exō , from ex “out.” Ultimately from an Indo-European base that is also the ancestor of English ex-, extra-, and extreme.]