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noun key·stone \ˈkē-ˌstōn\

Simple Definition of keystone

  • : a large stone at the top of an arch that locks the other stones in place

  • : something on which other things depend for support

Source: Merriam-Webster's Learner's Dictionary

Full Definition of keystone

  1. 1 :  the wedge-shaped piece at the crown of an arch that locks the other pieces in place — see arch illustration

  2. 2 :  something on which associated things depend for support <determination, a keystone of the puritan ethic — L. S. Lewis>

  3. 3 :  a species of plant or animal that produces a major impact (as by predation) on its ecosystem and is considered essential to maintaining optimum ecosystem function or structure

Examples of keystone in a sentence

  1. Tourism is the city's economic keystone.

  2. the keystone of his faith

Circa 1637

First Known Use of keystone

circa 1637

Other Architecture Terms

Rhymes with keystone

agon, aitchbone, alone, atone, backbone, Bastogne, bemoan, Big Stone, birthstone, Blackstone, bloodstone, bluestone, bondstone, Boulogne, breastbone, bridge loan, brimstone, brownstone, call loan, calzone, Capone, capstone, cell phone, cheekbone, chinbone, cogon, cologne, Cologne, colon, colón, Colón, condone, copestone, corn pone, curbstone, cyclone, daimon, dapsone, debone, depone, dethrone, dial tone, disown, Dordogne, downzone, dripstone, drop zone, drystone, earphone, earth tone, end zone, enthrone, estrone, fieldstone, firestone, Firestone, flagstone, flowstone, flyblown, footstone, freestone, free zone, full-blown, gallstone, gemstone, Gijón, goldstone, gravestone, greenstone, grindstone, hailstone, halftone, handblown, hard stone, headphone, headstone, hearthstone, high-flown, hip bone, homegrown, hormone, hornstone, impone, ingrown, inkstone, in stone, intone, jawbone, jewel tone, León, leone, life zone, limestone, lodestone, long bone, Maidstone, milestone, millstone, moonstone, mudstone, nose cone, oilstone, orgone, ozone, pay phone, peptone, pinbone, pinecone, piñon, pipestone, postpone, potstone, propone, redbone, red zone, rhinestone, sandstone, shade-grown, shinbone, siltstone, snow cone, soapstone, splint bone, strike zone, T-bone, tailbone, thighbone, time zone, toadstone, tombstone, touchstone, touch-tone, tritone, trombone, turnstone, twelve-tone, two-tone, Tyrone, unknown, unthrone, war zone, well-known, whalebone, wheel-thrown, whetstone, windblown, wishbone, Yangon

KEYSTONE Defined for Kids


noun key·stone \ˈkē-ˌstōn\

Definition of keystone for Students

  1. 1 :  the wedge-shaped piece at the top of an arch that locks the other pieces in place

  2. 2 :  something on which other things depend for support

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