rigor
     n 1: something hard to endure; "the asperity of northern winters"
          [syn: {asperity}, {grimness}, {hardship}, {rigour}, {severity},
           {rigorousness}]
     2: the quality of being logically valid [syn: {cogency}, {validity},
         {rigour}]
     3: excessive sternness; "severity of character"; "the harshness
        of his punishment was inhuman"; "the rigors of boot camp"
        [syn: {severity}, {harshness}, {rigour}, {inclemency}, {hardness},
         {stiffness}]
Source: WordNet® 2.0