gadfly vs pesterer

gadfly and pesterer both are nouns.

Word	Noun	Adjective	Verb	Adverb
gadfly	Yes	No	No	No
pesterer	Yes	No	No	No

As nouns, gadfly and pesterer are synonyms defined as:

Other synonyms of gadfly include blighter, cuss, pest.

gadfly (noun)	pesterer (noun)
any of various large flies that annoy livestock	a persistently annoying person
a persistently annoying person