gasbag vs windbag

gasbag and windbag both are nouns.

Word	Noun	Adjective	Verb	Adverb
gasbag	Yes	No	No	No
windbag	Yes	No	No	No

As nouns, gasbag and windbag are synonyms defined as:

gasbag and windbag: a boring person who talks a great deal about uninteresting topics

gasbag (noun)	windbag (noun)
the bag containing the gas in a balloon	a boring person who talks a great deal about uninteresting topics
a boring person who talks a great deal about uninteresting topics