Normally a short form of commuter rail, commuter train or commuter bus; A transport system or a vehicle in such systems used to transport commuters (#2)
To and from work and home.
Using public transport.
One who commutes (etymology 1).
A rail transport system with trains used to transport commuters between two places, typically their homes and works, normally within a metropolitan area and its surrounding environs, and generally distinguished from other rail transport systems (i.e. subways, metros, tramways) by having less frequent service, lacking free transfers between trains and using heavy rolling stock running on a mainline railway