gasbag

A bag or bladder to hold a reservoir of gas, as in a hot-air balloon.

In half an hour a good-sized gas-bag had been formed, and the jerking and straining upon the thongs showed that it was capable of considerable lift.

By this method of construction a considerable amount of support can be imparted to the gasbag, though it does not dispense with the services of the ballonet, as does the entirely rigid type.

A lighter-than-air aircraft; a balloon or dirigible.

A person who is overly garrulous or prone to making empty, unsupportable statements; a windbag.

Not that the Reverend James is absolutely a pretentious gasbag any more than Marchbanks is an inspired prophet. He has a definite, a positive part in the world's work.

You would think the fate of civilization itself rested on the outcome of my trial, based on some of those gasbags who were only too happy to speculate, postulate and pontificate about my situation.

To speak foolishly, pompously, or at length; to blather.

"You're a swell at it. I'll allow that. And I'll provide the gas-bagging." / "The gas-bagging?" I inquired. "What exactly do you mean?" / "What do I mean, you dear old sober-sides?" said Lyne. “I mean that I will do all the bow-wowing[…]"

You all see her flirtin and makin up to people and then they gasbag about it to make themselves important. But that's just her way. Underneath she's one of the most shy people you'd ever meet.