The term 'TRAIN LINE' can be broken down into three crossword solutions: RAILWAY (7 letters), RAIL (4 letters), and RAILROUTE (9 letters). RAILWAY is a noun that refers to a system of tracks, signals, and other equipment for the operation of trains. RAIL is a noun that refers to a bar or beam of metal that is used to form a track for trains or other vehicles to travel on. Finally, RAILROUTE is a noun that refers to a route or line of RAILWAY tracks. All three terms are related to the transportation of people and goods by train.