The storage of water that has been pumped to a higher level when demand for electricity is low so that its return to the lower level can be used to generate hydroelectricity when demand is high; frequently attributive.
Origin
1920s.
Definition of pumped storage in US English:
pumped storage
noun
The storage of water that has been pumped to a higher level when demand for electricity is low so that its return to the lower level can be used to generate hydroelectricity when demand is high; frequently attributive.