hydrogen balloon
noun1
A type of gas balloon filled with hydrogen gas, and able to fly higher and further than a hot-air balloon.
Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.
noun
A type of gas balloon filled with hydrogen gas, and able to fly higher and further than a hot-air balloon.
Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.
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