/pɒn'tu:n; pɑn`tun/
n any of a number of flat-bottomed boats or hollow metal structures joined together to support a temporary roadway over a river, an estuary, etc （作浮桥用的）平底船或金属空筒; 趸船
*[attrib 作定语] a pontoon bridge 浮桥.

/pɒn'tu:n; pɑn`tun/
n (also twenty-one, vingt-et-un) (Brit) (US `blackjack)
(a) card-game in which players try to acquire cards with a face value totalling
21 二十一点牌戏.
(b) (in this game) score of
21 from two cards （二十一点牌戏中）两张牌的点数之和为21点.

n
[Date: 1600-1700; Language: French;Origin: ponton 'floating bridge', from Latin ponto, from pons 'bridge']
[C]
one of several metal containers or boats that are fastened together to support a floating bridge
[C]
one of two hollow metal containers fastened to the bottom of a plane so that it can come down onto water and float
[U]BrE
a card game, usually played for money
American Equivalent: blackjack