Shuttle is a term used to describe a mode of transportation that involves short trips between two points. The most common form of shuttle is a BUS, which is a 3-letter word. Shuttle service is a type of transportation service that provides regular trips between two points, usually for a fee. This is a 14-letter word. Commuter traffic is the movement of people between their homes and places of work or study. This is a 15-letter word.