decree vs rule out

decree is a noun but rule out is not a noun.

Word	Noun	Adjective	Verb	Adverb
decree	Yes	No	Yes	No
rule out	No	No	Yes	No

As verbs, rule out is a hyponym of decree; that is, rule out is a word with a more specific, narrower meaning than decree:

decree: decide with authority
rule out: include or exclude by determining judicially or in agreement with rules

Other hyponyms of decree include override, overrule, overthrow, overturn, reverse, rule in.

decree (noun)	rule out (noun)
a legally binding command or decision entered on the court record (as if issued by a court or judge)

decree (verb)	rule out (verb)
decide with authority	dismiss from consideration or a contest
issue a decree	include or exclude by determining judicially or in agreement with rules
	make impossible, especially beforehand