Which term describes an open space of ground covered with grass and kept smoothly mown?

The term that describes an open space of ground covered with grass and kept smoothly mown is "lawn." A lawn is typically a well-maintained area that is specifically cultivated for recreational purposes or aesthetic appeal, often found in residential areas, parks, and other public spaces. Lawns are usually comprised of a variety of grass types and are characterized by their uniform height and lush green appearance due to regular mowing and care.

In contrast, while a park is a larger public space that may contain lawns, gardens, trees, and other landscaping elements, it does not specifically refer to the grassy area itself. A garden typically emphasizes cultivated plants, flowers, or vegetables, focusing more on plant arrangement and design than on just grass. A yard refers to an area around a house that may include a lawn but can also contain patios, flower beds, and other features beyond just the grassy area. Thus, the specific, well-defined focus on a smoothly mown grassy surface distinctly aligns with the definition of "lawn."