tormentor vs gadfly

tormentor and gadfly both are nouns.

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

As nouns, gadfly is a hyponym of tormentor; that is, gadfly is a word with a more specific, narrower meaning than tormentor:

Other hyponyms of tormentor include harasser, blighter, cuss, pest, pesterer, tantaliser, tantalizer, witch-hunter.

tormentor (noun)	gadfly (noun)
a flat at each side of the stage to prevent the audience from seeing into the wings	any of various large flies that annoy livestock
someone who torments	a persistently annoying person