gasbag

Short definition from Wiktionary

Noun

1. 1
   A bag or bladder to hold a reservoir of gas, as in a hot-air balloon.
2. 2
   A lighter-than-air aircraft; a balloon or dirigible.
3. 3
   A person who is overly garrulous or prone to making empty, unsupportable statements; a windbag.

Verb

1. 1
   To speak foolishly, pompously, or at length; to blather.