The trend is the underlying long-term movement lasting many years. The cycle, also called business cycle, is a quasi-periodic oscillation lasting for more than a year around the long-term trend. It is characterized by alternating periods of expansion and contraction. The trend and the cycle are difficult to estimate separately and thus are considered and analysed as a whole as the trend-cycle.
Eurostat, "Memobust Glossary" (part of the Memobust Handbook on Methodology of Modern Business Statistics), ESSnet "Memobust", March 2014