Deep Six

The Definition

To dispose of something permanently; to throw it away or destroy it. It implies a definitive end, where the object is not just discarded but made unrecoverable.

The Deep Dive

The phrase has its roots in the traditional maritime method of measuring water depth: the sounding line. Before electronic sonar, sailors would drop a lead weight attached to a rope (a "lead line") over the side of the ship. The rope was marked at intervals of six feet, known as fathoms.

If a sailor called out "by the mark six," the water was 36 feet deep. However, to "deep six" something meant to toss it overboard into water that was at least six fathoms deep. At 36 feet, in the era before scuba gear and advanced salvage, anything thrown overboard was considered gone for good.

There are two primary theories on how the phrase evolved into its modern "destruction" context:

  • The Burial Theory: Traditional maritime burials required the body to be sewn into a weighted shroud and dropped into deep water—specifically "six fathoms down"—to ensure the remains wouldn't wash back to shore or be disturbed by scavengers.

  • The Naval Disposal Theory: During the World Wars, the phrase was used by sailors to describe the disposal of hazardous materials or evidence. If you "deep-sixed" a piece of equipment or a document, you weren't just throwing it in the trash; you were ensuring it would never be seen by the enemy again.

The transition to civilian slang accelerated in the 1970's during the Watergate scandal, when it was famously used by White House counsel John Dean in reference to disposing of incriminating evidence.

Fast Facts

  • The Measurement: One fathom equals 6 feet (1.82 meters). Therefore, the "Deep Six" is exactly 36 feet deep.

  • The "Deep Nine": In some old naval traditions, a "Deep Nine" was also used, referring to nine fathoms (54 feet), used when the sounding lead hit a depth that wasn't exactly on a marked notch.

  • Political Infamy: The phrase became a household term in 1972 when it was suggested that certain files be "deep sixed" in the Potomac River.

References

  • Dean, J. W. (1976). Blind Ambition: The White House Years. Simon & Schuster.

  • Jeans, P. D. (2004). Ship to Shore: A Dictionary of Pictorial Maritime Grammar. McGraw-Hill.

  • Lavery, B. (1987). The Arming and Fitting of English Ships of War, 1600–1815. Naval Institute Press.

  • Safire, W. (2008). Safire's Political Dictionary. Oxford University Press.