WordNet (r) 3.0 (2006):

rigourousness
    n 1: something hard to endure; "the asperity of northern
         winters" [syn: asperity, grimness, hardship, rigor,
         rigour, severity, severeness, rigorousness,
         rigourousness]
    2: excessive sternness; "severity of character"; "the harshness
       of his punishment was inhuman"; "the rigors of boot camp"
       [syn: severity, severeness, harshness, rigor,
       rigour, rigorousness, rigourousness, inclemency,
       hardness, stiffness]