An economic expansion is an upturn in the level of economic activity and of the goods and services available. It is a finite period of growth, often measured by a rise in real GDP, that marks a reversal from a previous period, for example, while recovering from a recession.[1][2] The explanation of fluctuations in aggregate economic activity between expansions and contractions ("booms" and "busts" within the "business cycle") is one of the primary concerns of macroeconomics.[3]
I would define economic expansion as the increase of aggregate production from one production period to another. If the concept is defined in this general way it includes expansion that results from an increase in population, from better utilization [...].
[...] the primary focus of macroeconomics swung back from determining and manipulating the equilibrium level of output to the 'business cycle'.