Answer: Siphons

For a century, the definition of “siphon” in the Oxford English Dictionary read:

A pipe or tube of glass, metal or other material, bent so that one leg is longer than the other, and used for drawing off liquids by means of atmospheric pressure, which forces the liquid up the shorter leg and over the bend in the pipe.

In 2010, Dr. Stephen Hughes noticed the entry and checked several other dictionaries to see if the error was repeated: all of them indicated that atmospheric pressure was the force that drove a siphon when, in fact, it is gravity. Hughes conducted a series of tests to see how much of an impact (if any) atmospheric pressure had on the rate of water flow in a siphon, published the results in Scientific Reports, and contacted the Oxford English Dictionary to notify them that a correction was in order. They’ve since revised the entry to remove the reference to atmospheric pressure.