1. Relating to, resembling, or suggesting a balloon
2. Being or having a final installment that is much larger than preceding ones in a term or installment note

ETYM French ballon, aug. of balle ball: cf. Italian ballone. Related to Ball, Pallone.
Lighter-than-air craft that consists of a gasbag filled with gas lighter than the surrounding air and an attached basket, or gondola, for carrying passengers and/or instruments. In 1783, the first successful human ascent was in Paris, in a hot-air balloon designed by the Montgolfier brothers Joseph Michel and Jacques Etienne. In 1785, a hydrogen-filled balloon designed by French physicist Jacques Charles traveled across the English Channel.
Coal gas was substituted as a cheap alternative to hydrogen in 1821, and this allowed for voyages by later 19th-century and early 20th-century explorers, scientists, and fairground performers. By the 1920s and 1930s balloons were used for high-altitude scientific research, especially before the development of high-altitude aircraft and Earth-orbiting satellites; for other kinds of research and exploration they were found to be generally unreliable, since they cannot be guided but go where the wind blows. They have become popular for sport and continue in use as instrument-only observers for meteorology, and for monitoring infrared, ultraviolet, and gamma rays.
1. Large tough non-rigid bag filled with gas or hot air.
2. Small thin inflatable rubber bag with narrow neck.

1. To become inflated; SYN. inflate, billow.
2. To ride in a hot air balloon.