pontoon

¹ American  

[pon-toon] / pɒnˈtun /

Also ponton

noun

1. Military. a boat or some other floating structure used as one of the supports for a temporary bridge over a river.

2. a float for a derrick, landing stage, etc.

3. Nautical. a float for raising a sunken or deeply laden vessel in the water; a camel or caisson.

4. a seaplane float.

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pontoon ² American  

[pon-toon] / pɒnˈtun /

noun

British.

1. the card game twenty-one.

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pontoon ¹ British  

/ pɒnˈtuːn /

noun

1. 1. a watertight float or vessel used where buoyancy is required in water, as in supporting a bridge, in salvage work, or where a temporary or mobile structure is required in military operations

   2. ( as modifier )

      a pontoon bridge

2. nautical a float, often inflatable, for raising a vessel in the water

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pontoon ² British  

/ pɒnˈtuːn /

noun

1. Also called: twenty-one.   vingt-et-un.  a gambling game in which players try to obtain card combinations worth 21 points

2. (in this game) the combination of an ace with a ten or court card when dealt to a player as his first two cards

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Etymology

Origin of pontoon¹

1585–95; < French ponton < Latin pontōn- (stem of pontō ) flat-bottomed boat, punt

Origin of pontoon²

1915–20; alteration of French vingt-et-un twenty-one

Explanation

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."

Example Sentences

The last time, it was a Soviet-made pontoon bridge.

From The Wall Street Journal • Apr. 1, 2026

Rescue teams from Thursday used earth moving equipment on a pontoon to dredge a channel through the sand to allow the animal to escape.

From Barron's • Mar. 27, 2026

"I could smell gas leaking, some gentlemen helped take passengers off a pontoon boat that got stuck in the shore," Ms Brigantino said.

From BBC • Jun. 23, 2025

It all began when 57-year-old Billy was sitting in his house and spotted the cub diving off the nearby pontoon.

From BBC • Nov. 4, 2024

After they positioned the pontoon boat at the edge of the water, the workmen attached the iron tracks with the cannonballs in them.

From "The (Mostly) True Story of Cleopatra's Needle" by Dan Gutman