正如约翰·梅纳德·凯恩斯（John Maynard Keynes）在1930年代大萧条时首先观察到的那样，流动性陷阱描述了一个政策利率已达零点，却依旧无法刺激长期缺乏的总需求的状况。
First observed by John Maynard Keynes during the Great Depression of the 1930s, the liquidity trap describes a situation in which policy interest rates, having reached the zero bound, are unable to stimulate chronically deficient aggregate demand.