The sport, practice, or hobby of traveling in hot air balloons; also, rapid growth or expansion of something.
Present participle of 'balloon,' formed by adding '-ing' to the verb; refers both to the literal activity and the metaphorical concept of rapid expansion.
Ballooning tournaments date back to the 1900s, and modern hot air balloon pilots compete in precision events and cross-continent races—it's a sport older than powered flight.
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