|well (wěl) Pronunciation Key
A deep hole or shaft sunk into the Earth to tap a liquid or gaseous substance such as water, oil, gas, or brine. If the substance is not under sufficient pressure to flow freely from the well, it must be pumped or raised mechanically to the surface. Water or pressurized gas is sometimes pumped into a nonproducing oil well to push petroleum resources out of underground reservoirs. See also artesian well.