pon·toon 
/pɑnˈtu:n/ noun
plural pon·toons /pɑnˈtu:n/ noun [count] : a large hollow container filled with air that is used to make a structure (such as a boat, airplane, or bridge) float on top of water
▪ The boat had two pontoons. ▪ They built a pontoon bridge. [=a bridge that floats on the water and is held up by pontoons] ▪ a pontoon plane [=an airplane that has pontoons on the bottom so that it can float on water]
▪ The boat had two pontoons. ▪ They built a pontoon bridge. [=a bridge that floats on the water and is held up by pontoons] ▪ a pontoon plane [=an airplane that has pontoons on the bottom so that it can float on water]
