cancel vs strike down

cancel is a noun but strike down is not a noun.

Word	Noun	Adjective	Verb	Adverb
cancel	Yes	No	Yes	No
strike down	No	No	Yes	No

As verbs, cancel and strike down are synonyms defined as:

cancel (noun)	strike down (noun)
a notation cancelling a previous sharp or flat

cancel (verb)	strike down (verb)
make invalid for use	cause to fall by or as if by delivering a blow
remove or make invisible	cause to die, especially suddenly
declare null and void; make ineffective	declare null and void; make ineffective
postpone indefinitely or annul something that was scheduled
make up for