Dictionary.net

• a well drilled through impermeable strata into strata that receive water from a higher altitude so there is pressure to force the water to flow upward

2006 - WordNet 3.0
By Princeton University

• a well drilled through impermeable strata into strata that receive water from a higher altitude so there is pressure to force the water to flow upward

2011 - English Dictionary Database
By DataStellar Co., Ltd