Plural of culvert; multiple arched structures or tunnels that carry water under roads, railways, or embankments.
From culvert (an arched watercourse), which may derive from Old French coulvert (covered), though etymology is disputed. The word emerged in English in the 17th-18th centuries as civil engineering terminology.
A culvert is such an ordinary infrastructure piece that we ignore it, but thousands of them quietly do essential work under our streets and highways, and the word itself has a mystery—nobody is completely sure where it came from, which is unusual for a technical term.
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