reject vs rule out

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

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

As verbs, reject and rule out are synonyms defined as:

Other synonyms of reject include eliminate, winnow out.

reject (noun)	rule out (noun)
the person or thing that is rejected or set aside as inferior in quality

reject (verb)	rule out (verb)
not accept something given or offered	dismiss from consideration or a contest
dismiss from consideration or a contest	include or exclude by determining judicially or in agreement with rules
deem wrong or inappropriate	make impossible, especially beforehand
reject with contempt
not accept as true
refuse entrance or membership
resist immunologically the introduction of some foreign tissue or organ