A pontoon is a flat boat that floats with the help of hollow tubes, also called pontoons. A lakeside resort might have pontoons and canoes that you can rent for the day.

The feature that distinguishes a pontoon, or pontoon boat, is the use of airtight cylinders to keep it buoyant. You can call these structures pontoons or floats, and they're used for things like houseboats, and some seaplanes that can land on water — and float there, thanks to pontoons. Sometimes pontoons are also used to support bridges and docks. The word stems from the Latin pontonem, "flat-bottomed boat," and its root pons, or "bridge."

Definitions of pontoon

n (nautical) a floating structure (as a flat-bottomed boat) that serves as a dock or to support a bridge

Type of:
barge, flatboat, hoy, lighter
a flatbottom boat for carrying heavy loads (especially on canals)

n a float supporting a seaplane

Type of:
something that floats on the surface of water

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