decompression

Etymology

It is formed from English de- + compression,^[2][3][4][5] with the prefix in its sense of reversing an action.^[2][5] Merriam-Webster and Dictionary.com take it as probably from French décompression, formed from dé- and compression.^[6][7] Compression itself is from Old French compression and Latin compressiō (“a pressing together”), from comprimō (“to squeeze”).^[3][2]

Earliest recorded meaning

The reduction of the pressure of the air or another gas in an enclosed space, especially the return of a diver or caisson worker from compressed air to normal pressure: 1905, in a heading in the Journal of Physiology.^[2][3][4] Dictionary.com dates the word to 1900–05,^[7] and Etymonline finds decompression chamber by 1903.^[3]

Semantic evolution

The word belongs to the physiology of work in compressed air: Merriam-Webster describes the drop in pressure met by a construction worker leaving a caisson through an air lock, by an aviator climbing to a great height, and by a diver rising quickly.^[6] The Shorter Oxford separates the controlled return of a diver to normal pressure from the sudden loss of pressure in an aircraft.^[5] In 1906 surgery took it up for relieving excessive pressure inside a part of the body, especially by removing a flap of the skull.^[2][8] A figurative sense, recovering from a stressful or confining situation, is recorded from 1951 and was originally North American,^[2] and computing added the expansion of compressed files or signals in 1967.^[2][5][9] Compounds include decompression chamber and decompression sickness, the condition caused by too rapid decompression, which includes the bends.^[5]

Timeline

• 1905 – reduction of the pressure of air in an enclosed space, especially for a diver.^[2][3][4]
• 1906 – the surgical relief of excessive internal pressure.^[2]
• 1951 – recovery from a stressful or restrictive situation.^[2]
• 1967 – in computing, the expansion of compressed files or signals.^[2]

Meanings

Noun

1. A reduction in air pressure, as in an aircraft cabin.^[9][6][5]
2. The gradual return of a diver or other person who has been under high pressure to normal atmospheric pressure.^[9][5][6]
3. (surgery) An operation to relieve pressure on an organ or part, such as the brain or the spinal cord.^[8][2][6]
4. (computing) The expansion of data that has been compressed back to its normal size.^[9][5][2]
5. Relaxation after a period of stress or confinement.^[2]

Word family

• decompression chamber
• decompression sickness

Related words

• compression
• decompress
• compress

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m n Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
5. ^ a b c d e f g h Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
6. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
8. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
9. ^ a b c d Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press