pontoon

A flat-bottomed boat or other floating structure used as a buoyant support for a temporary bridge, dock or landing stage.

Thanks to the previous experience of the chief performers, to careful preparation and rehearsal, and to perfect weather conditions, they watched in breath-bated silence the spectacle of the huge bulk moving without a hitch into position over the temporary pier caps on which it settled as water ballast was admitted to the pontoons.

A bridge with floating supports.

A box used to raise a sunken vessel.

A float of a seaplane.

A lighter or barge used for loading or unloading ships.

A card game in which the object is to obtain cards whose value adds up to, or nearly to, 21 but not exceed it.