noun
A bag or bladder to hold a reservoir of gas, as in a hot-air balloon.
(by extension) A lighter-than-air aircraft; a balloon or dirigible.
(figuratively, derogatory) A person who is overly garrulous or prone to making empty, unsupportable statements; a windbag.
verb
(informal, intransitive) To speak foolishly, pompously, or at length; to blather.