A culvert is a drain — but not of the kinds that drain your bathtub or empties your bank account. A culvert is any kind of channel or tunnel that directs unwanted water away from roads and other corridors of travel.
A culvert is typically built underground to prevent inconveniently located streams and rain runoff from flooding roads, highways, streets, and railroads. Culvert can also be used as a verb: if water pools in your driveway and then seeps into the foundation of your house, soaking the brand-new carpet in the basement that you thought you’d just waterproofed, you might wonder why the builders didn’t culvert that underground stream.