A grass mat is a type of ground cover made from natural grasses and other plants. It is often used to provide a soft, comfortable surface for outdoor activities such as picnics or camping. The term 'grass mat' can also be used to refer to a type of artificial turf, which is made from synthetic materials. The crossword solution for the term 'grass mat' is SOD, which stands for SOD, a type of grass-covered soil. SOD is typically used to create a lawn or other grassy area.