pontoon

noun7

1. •
   A flat-bottomed boat or other floating structure used as a buoyant support for a temporary bridge, dock or landing stage.
2. •
   A box used to raise a sunken vessel.
3. •
   A float of a seaplane.
4. •
   A bridge with floating supports.
5. •
   A card game in which the object is to obtain cards whose value adds up to, or nearly to, 21 but not exceed it.
6. •
   A lighter or barge used for loading or unloading ships.
7. •
   A two-card hand totalling 21 in this game.