Etymology From Middle French tonnelle (“net”) or tonel (“cask”), diminutive of Old French tonne (“cask”), a word of uncertain origin and affiliation. Related to Old English tunne (“tun; cask; barrel”). More at tun.
In 1865 an outfit called the East London Railway Company bought the Brunel tunnel for £800,000, and in 1869 they opened a railway through it.2012, Andrew Martin, Underground Overground: A passenger's history of the Tube, Profile Books, →ISBN, page 90:
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A passage through or under some obstacle.
But very soon he grew to like it, for the Boy used to talk to him, and made nice tunnels for him under the bedclothes that he said were like the burrows the real rabbits lived in.1921 June, Margery Williams, “The Velveteen Rabbit: Or How Toys Become Real”, in Harper’s Bazar, volume LVI, number 6 (2504 overall), New York, N.Y.: International Magazine Company, →ISSN, →OCLC:
Tunnels often feature in fictional journeys, so I will end with quotations from a fairly recent novel, Howard Spring's "Fame is the Spur", published in 1940, in which there is a journey from Manchester to Bradford via the Calder Valley route: "Ay, we're going through Todmorden. We'll soon be in t' tunnel, and when we get to t' other end we'll be in Yorkshire," and "Ah think this is t' filthiest tunnel in t' world."1957 May 23, Neil Caplan, “Railways in English Fiction”, in Railway Magazine, page 350:
1 more example
There are more than 1,500 railway tunnels in Britain and the majority are still in use, carrying working tracks beneath Britain's most inconvenient geographic features.2020 August 26, Tim Dunn, “Great railway bores of our time!”, in Rail, page 42:
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A hole in the ground made by an animal, a burrow.
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Computing, Engineering, Mathematics, Natural sciences, Networking, Physical sciences, Sciences A wrapper for a protocol that cannot otherwise be used because it is unsupported, blocked, or insecure.
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A vessel with a broad mouth at one end, a pipe or tube at the other, for conveying liquor, fluids, etc., into casks, bottles, or other vessels; a funnel.
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The opening of a chimney for the passage of smoke; a flue.
And one great chimney, whose long tonnell thence, / The smoke forth threw1590, Edmund Spenser, “Book II, Canto IX”, in The Faerie Queene. […], London: […] [John Wolfe] for William Ponsonbie, →OCLC, stanza 29:
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Business, Mining A level passage driven across the measures, or at right angles to veins which it is desired to reach; distinguished from the drift, or gangway, which is led along the vein when reached by the tunnel.
Especially in the Eden Valley, trees create what is almost a green tunnel (particularly in summer).2021 October 20, Mark Rand, “S&C: a line fit for tourists... and everyone?”, in RAIL, number 942, page 43:
Etymology From Middle French tonnelle (“net”) or tonel (“cask”), diminutive of Old French tonne (“cask”), a word of uncertain origin and affiliation. Related to Old English tunne (“tun; cask; barrel”). More at tun.
1
To make a tunnel through or under something; to burrow.
The 1955 Act gave powers for compulsory acquisition of "easements", or permission to tunnel beneath dwelling houses instead of, as had previously been necessary, following approximately the course of surface roads.1962 October, “London gets its Victoria tube”, in Modern Railways, page 258:
The 6.5km route is agreed from a junction with the relief lines of the Great Western main line to the west of Slough, the new link would tunnel under the M25 to reach Heathrow's Terminal 5 station, where space has been set aside to accommodate services from the west.2019 October, Ruth Bagley tells James Abbott, “Crunch time for Heathrow western link”, in Modern Railways, page 74:
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To dig a tunnel.
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Computing, Engineering, Mathematics, Natural sciences, Networking, Physical sciences, Sciences To transmit something through a tunnel (wrapper for an insecure or unsupported protocol).
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Medicine, Sciences To insert a catheter into a vein to allow long-term use.
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Natural sciences, Physical sciences, Physics To undergo the quantum-mechanical phenomenon where a particle penetrates through a barrier that it classically cannot surmount.