Kondratieff Wave

In economics, Kondratiev waves—also called grand supercycles, surges, long waves, or K-waves—are regular, sinusoidal cycles in the modern (capitalist) world economy. Fifty to sixty years in length, the cycles consist of alternating periods between high sectoral growth and periods of slower growth. This business cycle is more visible in international production data than in individual national economies and concerns output rather than prices. Some economists divide the Kondratiev wave into two 'seasons', namely, the Kondratiev Fall and the later part, the Kondratiev Winter. A bull market is associated with 'fall' and a bear market with 'winter'. More common today is the division into four periods with a turning point (collapse) between the first and second two.
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An economic theory of the Soviet economist Kondratieff stating that the economies of the western world are susceptible to major up-and-down "supercycles" lasting 50 to 60 years.