countermand vs vacate

countermand is a noun but vacate is not a noun.

Word	Noun	Adjective	Verb	Adverb
countermand	Yes	No	Yes	No
vacate	No	No	Yes	No

As verbs, countermand and vacate are synonyms defined as:

Other synonyms of countermand include annul, lift, overturn, repeal, rescind, reverse, revoke.

countermand (noun)	vacate (noun)
a contrary command cancelling or reversing a previous command

countermand (verb)	vacate (verb)
cancel officially	cancel officially
	leave behind empty; move out of
	leave (a job, post, or position) voluntarily