Era ( lat.aera ):
- In chronology, this is the starting point of the reckoning , for example: the Christian era , the Muslim era ( hijra ), the era of Diocletian , the era of the Seleucids , the era “ from the founding of Rome ”, etc. (See List of dates of the beginning of various eras ). A longer period of time than the era .
- Geological era - the period of time of geological history during which an erathema (group) was formed; subdivided into geological periods ; several eratems are combined into aeon . For example: Paleozoic , Mesozoic , Cenozoic era .
- Astrological era - 1/12 of the period of the precession of the earth's axis , for example: the era of Aquarius , etc.