oil well

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A hole drilled or dug in the earth from which petroleum flows or is pumped. Also called oiler.

Century Dictionary and Cyclopedia

1. n. A boring made for petroleum. This is the name by which such borings in various oil-producing regions, and especially in Pennsylvania, are most generally designated. Borings which are unsuccessful, or which do not furnish any oil, are called dry wells. See petroleum.
2. n. An oil-cellar; a dish or receptacle, under a bearing, filled with oil to furnish a supply for the bearing.

Wiktionary

1. n. A hole drilled into the earth from which petroleum is pumped

GNU Webster's 1913

1. n. A well{3} from which petroleum is or has been extracted; a well{3} drilled deeply into an oil-bearing geological formation specifically for the purpose of obtaining petroleum.

WordNet 3.0

1. n. a well that yields or has yielded oil