nag vs harridan

nag and harridan both are nouns.

Word	Noun	Adjective	Verb	Adverb
nag	Yes	No	Yes	No
harridan	Yes	No	No	No

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

nag: someone (especially a woman) who annoys people by constantly finding fault
harridan: a scolding (even vicious) old woman

nag (noun)	harridan (noun)
an old or over-worked horse	a scolding (even vicious) old woman
someone (especially a woman) who annoys people by constantly finding fault

nag (verb)	harridan (verb)
remind or urge constantly
bother persistently with trivial complaints
worry persistently