Etymologically
Log in

keystone

This is the current revision of this entry, as edited by bogdan on 31 October 2026 at 13:27. This address is a permanent link to this version.
Changes in this edit History

Pronunciation

  • /ˈkiː.stəʊn/[1]

Etymology

It is formed from English key + stone.[2][3][4][5][6] Etymonline explains key either in its figurative sense "that which holds other parts together" or in its Middle English sense in building, an ornament at the meeting of the ribs of a vault (mid 14th century); being the last stone put in, the keystone was thought of as locking, or "keying", the whole structure.[7] The stone was earlier called simply a key (1520s).[7] The OED thinks it very unlikely that the surname of one Willelmus Keistan (1202) shows an earlier use.[2]

Earliest recorded meaning

The central stone at the top of an arch or vault, which locks the rest together: before 1637, in Ben Jonson's Underwoods.[2][4][7]

Semantic evolution

The figurative use, a person or thing in a high or vital position, followed almost at once, in 1641,[2][7] and by 1722 the word meant the central principle of a system on which the rest depends.[2][3] Pennsylvania was nicknamed the Keystone State, recorded as old Keystone in 1839,[2] because of its central place among the original states along the Atlantic.[7]^(Popik|"Pennsylvania: Keystone State (nickname)", 12 February 2016) Technical senses followed in the 19th century: a block in a smelting furnace (1821–70), a bond-stone in a wall (1823), and in colour lithography a stone carrying the key drawing (1854).[2][3] An American adjective use, "central, vital", and a verb, to provide with or act as a keystone, appeared in 1846.[2][4] In the 20th century the verb also meant to distort an image into a trapezoid by the keystone effect.[2][3]

Timeline

  • 1520s – key, the central stone of an arch.[7]
  • before 1637 – the central stone of an arch.[2][4]
  • 1641 – figuratively, a person or thing in a vital position.[2]
  • 1722 – the central principle of a system.[2]
  • 1823 – a bond-stone in a wall.[2]
  • 1839 – Pennsylvania, the Keystone State.[2]
  • 1846 – adjective, central, vital; verb, to provide with a keystone.[2][4]
  • 1854 – the key stone in colour lithography.[2]
  • 1937 – verb, to distort an image into a trapezoid.[2]

Meanings

Noun

  1. The wedge-shaped stone at the top of an arch, put in last and locking the others in place.[4][3][2][6]
  2. The central part or principle on which everything else depends: Trust is the keystone of the partnership.[4][3][2]
  3. Printing: in colour lithography, the stone carrying the key drawing, used as a guide.[3][2]
  4. A bondstone connecting the layers of a wall.[4][2]
  5. Small crushed stone used to fill the gaps between larger stones in a road surface.[4]

Adjective

  1. (originally US) Central; vital.[2]

Verb

  1. To support with, or act as, a keystone; figuratively, to hold together.[4][2]
  2. Cinematography, television: to distort an image into a trapezoid by projecting it at an angle.[3][2]

Word family

  • Keystone State

Usage notes

Capitalized, Keystone refers to Keystone Studios, founded in 1912, whose comedies featured the incompetent Keystone Kops;[2][7] in American slang a Keystone is a police officer, from 1929.[8][2]

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 o p q r s t u v w x y z Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  3. ^ 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
  4. ^ a b c d e f g h i j Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  5. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
  6. ^ a b Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
  7. ^ a b c d e f g Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  8. ^ Green, Jonathon (2010), Green's Dictionary of Slang, London: Chambers; digital ed. 2016–, https://greensdictofslang.com