Synonyms for Era (same or very similar meaning)
WordNet sense 1 (a period marked by distinctive character or reckoned from a fixed point or event):
epochWordNet sense 2 (a major division of geological time; an era is usually divided into two or more periods):
geological eraWordNet sense 3 ((baseball) a measure of a pitcher's effectiveness; calculated as the average number of earned runs allowed by the pitcher for every nine innings pitched):
earned run averageFrom the ODE community, based on WordNetadd/edit