Other forms: mass marketing; mass markets; mass marketed
Mass market is a term for a big group of people who are all interested in buying the same thing. There is a slowly growing mass market for all-electric vehicles.
As a verb, mass market means to sell something on a large scale. Your friendship bracelets may be selling well through word of mouth, but if you want to turn your business into a huge money-making venture, you'll have to produce thousands and mass market them. Economists differentiate between a mass market, with a big, varied group of consumers (a mass of people), and a niche market, a smaller, more specific group with common interests or characteristics.