mindmap root((时代)) period may designate an extent of time of any length: ~s of economic prosperity. epoch applies to a period begun or set off by some significant or striking quality, change, or series of events: the steam engine marked a new ~ in industry. era suggests a period of history marked by a new or distinct order of things: the ~ of global communications. age is used frequently of a fairly well-defined period dominated by a prominent figure or feature: the ~ of Samuel Johnson.