rigourousness vs rigour

rigourousness and rigour both are nouns.

Word	Noun	Adjective	Verb	Adverb
rigourousness	Yes	No	No	No
rigour	Yes	No	No	No

As nouns, rigourousness and rigour are synonyms defined as:

Other synonyms of rigourousness include asperity, grimness, hardship, rigor, rigorousness, severeness, severity.

As nouns, rigourousness and rigour are synonyms defined as:

Other synonyms of rigourousness include hardness, harshness, inclemency, rigor, rigorousness, severeness, severity, stiffness.

rigourousness (noun)	rigour (noun)
something hard to endure	something hard to endure
excessive sternness	the quality of being valid and rigorous
	excessive sternness