pontoon

Concise Oxford English Dictionary © 2008 Oxford University Press:
pontoon1 /pɒnˈtuːn/

▶noun Brit. the card game blackjack or vingt-et-un.

■ a hand of two cards totalling 21 in this game.

– origin early 20th cent.: prob. an alt. of vingt-et-un ‘twenty-one’.

Concise Oxford English Dictionary © 2008 Oxford University Press:
pontoon2 /pɒnˈtuːn/

▶noun

• 1 a flat-bottomed boat or hollow metal cylinder used with others to support a temporary bridge or floating landing stage.

  ■ a bridge or landing stage supported by pontoons.

• 2 a large flat-bottomed barge or lighter equipped with cranes and tackle for careening ships and salvage work.

• 3 either of two floats fitted to an aircraft to enable it to land on water.

– origin C17: from Fr. ponton, from L. ponto, ponton-, from pons, pont- ‘bridge’.