rain garden
n.— «But he knew very little about native plants until about five years ago, when he encountered for the first time the term “rain garden”—a phrase used to describe an intentionally created depression in the ground that is planted with native species. Its purpose is to hold rainwater, allowing it to soak into the ground, preventing runoff.» —“Mays: ’shamefully ignored’ natives” by Alma Gaul Quad-City Times (Davenport, Iowa) Jan. 18, 2008. (source: Double-Tongued Dictionary)