An underground passageway, chamber, or series of chambers, sometimes having a roof of stone slabs, built as part of an ancient settlement or fort, especially in the British Isles.
[Earlier, any underground passage or storeroom, from French, from Old French, sozterrain (formed on the model of Latin subterrāneus, underground) : soz, under (from Latin subtus, from sub; see upo in the Appendix of Indo-European roots) + terre, earth (from Latin terra; see ters- in the Appendix of Indo-European roots).]
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