Epoch
Part of speech: noun
Definition: A particular period of history, especially one considered remarkable or noteworthy. A notable event which marks the beginning of such a period. A precise instant of time that is used as a reference point. A precise instant of time that is used as a reference point (e.g. January 1, 1970, 00:00:00 UTC).
Example sentence: The ideas of the ruling class are in every epoch the ruling ideas, i.e., the class which is the ruling material force of society, is at the same time its ruling intellectual force.
Era
Part of speech: noun
Definition: A time period of indeterminate length, generally more than one year.
Example sentence: 'Drip' is just another word for swag. Swag was not our word - my era is drip; that's our swag.