The everyday modern meaning: a small inflatable rubber or plastic balloon used as a toy, party decoration, etc.
The children are playing by blowing up balloons.
I bought colorful balloons for the party.
Dated original meaning referring to a large balloon for flight, such as a hot-air balloon or gas balloon. Modern Japanese usually uses 気球 for this.
See also: 気球
In the 19th century, attempts were made to travel the sky by balloon.
I blew up balloons for the birthday party.
The balloon burst with a loud bang.
At the end of the event, hundreds of balloons were released into the sky.
After a few days, the balloon deflated.
rubber balloon