listen to the pronunciation of gasbag
Englisch - Englisch
A bag or bladder to hold a reservoir of gas, as in a hot-air balloon

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.

Metaphorically, a person who is overly garrulous or prone to making empty, unsupportable statements

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.

someone who talks too much = windbag
envelope: the bag containing the gas in a balloon
a boring person who talks a great deal about uninteresting topics
{i} bag that contains the gas in an airship or balloon; windbag; boring person who talks too much, braggart (Informal)
plural of gasbag