cancel vs countermand

cancel and countermand both are nouns.

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

As verbs, countermand is a hyponym of cancel; that is, countermand is a word with a more specific, narrower meaning than cancel:

cancel (noun)	countermand (noun)
a notation cancelling a previous sharp or flat	a contrary command cancelling or reversing a previous command

cancel (verb)	countermand (verb)
make invalid for use	cancel officially
remove or make invisible
declare null and void; make ineffective
postpone indefinitely or annul something that was scheduled
make up for