जब अंतर्राष्ट्रीय स्तर पर वस्तुओ और सेवाओ के उत्पादन में निरन्तर गिरावट हो रही हो और सकल घरेलू उत्पाद कम से कम तीन महीने डाउन ग्रोथ में हो तो इस स्थिति को विश्व आर्थिक मन्दी कहते हैं। सन् 1929 में शुरुआती आर्थिक मंदी आधुनिक विश्व के आर्थिक इतिहास में सर्वाधिक गंभीर उथल पुथल में से एक थी

An economic depression is a period of carried long-term economic downturn that is the result of lowered economic activity in one major or more national economies. Economic depression maybe related to one specific country where there is some economic crisis that has worsened but most often reflexes historically the American Great Depression and similar economic status that may be recognized as existing at some country, several countries or even in many countries. It is often understood in economics that economic crisis and the following recession that maybe named economic depression are part of economic cycles where the slowdown of the economy follows the economic growth and vice versa. It is a result of more severe economic problems or a downturn than the recession itself, which is a slowdown in economic activity over the course of the normal business cycle of growing economy.