• In economics, inflation is the rise in the general level of prices.
• In cosmology, astrophysics, and astronomy, inflation (cosmic inflation) is the idea—first proposed by Alan Guth (1981)—that the nascent universe passed through a phase of exponential expansion that was driven by a negative positive energy density (with negative vacuum pressure).
• With respect to a system of matter, inflation is distention of matter by a fluid or gas.