Etymology From Middle English lynspin, compound of lins (“axletree”) and pin, from Old English lynis (“lynchpin”), from Proto-West Germanic *lunis, from Proto-Germanic *lunaz – compare German Lünse and Dutch luns – from Proto-Indo-European. Possible further cognates are Welsh olwyn (“wheel”), Old Armenian ողն (ołn, “back; spine, backbone”) and Sanskrit आणि (āṇí, “lynchpin”). Figurative use attested from the mid-20th century.
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A pin inserted through holes at the end of an axle or shaft, so as to secure a wheel or shaft-mounted device.
In ij camellis ferri vocatis lynspins emptis pro carectis iiijᵈ.1376–7, Compotus Roll Hyde Manor (In the manuscript deeds of Westminster Abbey)
Every design that villany could suggest was had recourse to in the hopes of nobbling Wild Dayrell; but never being left for an hour by either his trainer or jockey, he escaped the intended “coopering,” even when the lynchpins of the wheels of his van had been tampered with.1864 June 23, Baily's Magazine of Sports & Pastimes, volume 8, page 110:
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The axles were attached to the wooden floors with leather straps, the floor projecting on each side to take the wheels which were secured by linchpins to their outer faces.1971, Gwen White, Antique Toys And Their Background, page 79:
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Figuratively A central cohesive source of stability and security; a person or thing that is critical to a system or organisation.
What is difficult to appreciate, however, is the discrepancy between his statement to the 'Manchester Guardian' correspondent and his known abhorance for party politics, which is the lynchpin of modern democracy.1958, The Eastern Economist:
Community nurses have been described as the lynchpins of palliative care in the community.2013, Dvaid Sines, Community and Public Health Nursing, page 2006:
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Second, QAnon, whose adherents have deep ties to countless other large communities, has become a linchpin in that ecosystem, and the absurdity of its claims in no way reduces its political influence.2020 October 20, Renée DiResta, “The Right’s Disinformation Machine Is Getting Ready for Trump to Lose”, in The Atlantic:
Etymology From Middle English lynspin, compound of lins (“axletree”) and pin, from Old English lynis (“lynchpin”), from Proto-West Germanic *lunis, from Proto-Germanic *lunaz – compare German Lünse and Dutch luns – from Proto-Indo-European. Possible further cognates are Welsh olwyn (“wheel”), Old Armenian ողն (ołn, “back; spine, backbone”) and Sanskrit आणि (āṇí, “lynchpin”). Figurative use attested from the mid-20th century.
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Ambitransitive To adopt as, or serve as, a central cohesive source of stability and security.
The poems turn fear of individual death into an audit of the costs of an aristocratic status quo which is linchpinned by a monarchy indulging in paradigms of social redress that have become cosmetic, opportunities for self-display rather than genuine justice.2013, Christine Chism, Alliterative Revivals, page 238: