forbiddance vs test ban

forbiddance and test ban both are nouns.

Word	Noun	Adjective	Verb	Adverb
forbiddance	Yes	No	No	No
test ban	Yes	No	No	No

As nouns, test ban is a hyponym of forbiddance; that is, test ban is a word with a more specific, narrower meaning than forbiddance:

forbiddance: an official prohibition or edict against something
test ban: a ban on the testing of nuclear weapons that is mutually agreed to by countries that possess nuclear weapons

forbiddance (noun)	test ban (noun)
the action of prohibiting or inhibiting or forbidding (or an instance thereof)	a ban on the testing of nuclear weapons that is mutually agreed to by countries that possess nuclear weapons
an official prohibition or edict against something