A spreading device is a tool used to evenly distribute a substance, such as paint, over a surface. The term 'spreading device' can refer to a variety of tools, including brushes, rollers, and spatulas. The crossword solution for the term 'spreading device' is 'spacer, ' which is a tool used to create even spaces between objects. Spacers are commonly used in construction and carpentry to ensure that two pieces of material are evenly spaced apart.