elephant
n.— «Though more than a thousand discoveries are made in the U.S. yearly, “elephant fields”—those containing proven recoverable reserves of 100 million barrels of oil, one trillion cubic feet of gas, or the equivalant in mixed reserves—are rare. » —“Hottest U.S. Hydrocarbon Hunt Is In Western Rock Formation” Wall Street Journal Aug. 27, 1979. (source: Double-Tongued Dictionary)
Further reading
Asthenosphere, a geologist’s term for the molten layer beneath the earth’s crust, sparks a journey that stretches all the way from ancient Greece to the author of Uncle Tom’s Cabin. Plus: What the heck is a dogberg? It’s when...
What exactly is a planet? Controversy over this question led to Pluto’s redefinition, along with a brand-new English word. And: Some people now use the phrase all the things! to mean and whatnot or you know what I mean. This new sense of all...