The term 'road block' can be broken down into two crossword solutions: JAM (3 letters) and CURBSTONE (9 letters). JAM is a noun that refers to a situation in which progress is stopped or hindered, usually due to a large number of people or vehicles in a confined space. It is often used to describe traffic congestion. On the other hand, curbstone is a noun that refers to a stone or concrete block that lines the edge of a road or sidewalk. It is used to separate the road from the sidewalk and to provide a barrier between the two.