Is a pattern of irregular yet repeated flow of expansion and contraction of aggregate economic activity.

business cycle is defined as an "up and down movement" - this corresponds to expansion and contraction. This expansion and contraction is measured for example in the Gross Domestic Product (GDP) of a country.

This is a business cycle.

A business cycle is defined as an "up & down movement" that corresponds to expansion and contraction

Business cycles last from 2 to 12 years.