overrule vs overthrow

overrule is not a noun while overthrow is a noun.

Word	Noun	Adjective	Verb	Adverb
overrule	No	No	Yes	No
overthrow	Yes	No	Yes	No

As verbs, overrule and overthrow are synonyms defined as:

Other synonyms of overrule include override, overturn, reverse.

overrule (noun)	overthrow (noun)
	the termination of a ruler or institution (especially by force)
	the act of disturbing the mind or body

overrule (verb)	overthrow (verb)
rule against	rule against
	cause the downfall of; of rulers