气球的英文复数是 balloons.
其来源：Balloon这个词最早被记录在17世纪末，是从法语“ballon”一词演变而来，最初指的是大气球。
一些例句：
The children were having fun playing with the balloons.
(孩子们正在玩气球玩得很开心。)
We need more balloons for the party decorations.
(我们需要更多的气球来装饰派对。)
The balloons floated up into the sky.
(气球飘向天空。)