society > travel > travel by water > vessel, ship, or boat > vessel for transporting people or goods > passenger vessel > [noun] > water-bus (4)
a boat (originally a steamboat, later more usually a motor boat) carrying paying passengers as part of a scheduled service.
In Venice, a canal motor-boat (originally steamboat), used as a form of public transport.
In Italy: a motor boat, esp. one used to carry passengers on the Venetian canals.