veto vs debar

veto is a noun but debar is not a noun.

Word	Noun	Adjective	Verb	Adverb
veto	Yes	No	Yes	No
debar	No	No	Yes	No

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

Other hyponyms of veto include ban, bar, exclude, enjoin, criminalise, criminalize, illegalise, illegalize, outlaw.

veto (noun)	debar (noun)
a vote that blocks a decision
the power or right to prohibit or reject a proposed or intended act (especially the power of a chief executive to reject a bill passed by the legislature)

veto (verb)	debar (verb)
command against	prevent from entering; keep out
vote against; refuse to endorse; refuse to assent	prevent the occurrence of; prevent from happening; to protect from or to keep away anything undesirable; to ward off
	bar temporarily; from school, office, etc.