1. (

• era ,
• epoch

) a period marked by distinctive character or reckoned from a fixed point or event ;

2. (

• epoch ,
• date_of_reference

) (astronomy) an arbitrarily fixed date that is the point in time relative to which information (as coordinates of a celestial body) is recorded ;

3. (

• epoch ,

) a unit of geological time that is a subdivision of a period and is itself divided into ages ;