These nouns refer to a portion or length of time. Period is the most general: a short waiting period; a difficult period of my life; the Romantic period in music.Epoch refers to a period regarded as being remarkable or memorable: “We enter on an epoch of constitutional retrogression” (John R. Green). An era is a period of time notable because of new or different aspects or events: “How many a man has dated a new era in his life from the reading of a book” (Henry David Thoreau). An age is usually a period marked by a distinctive characteristic: the age of Newton; the Iron Age. A term is a period of time to which limits have been set: Senators are elected for a term of six years.