say it: RIG-ur
rigor is a noun meaning "something hard to endure". It carries 3 recorded senses.
something hard to endure
“the asperity of northern winters”
the quality of being valid and rigorous
excessive sternness
“severity of character”
“the harshness of his punishment was inhuman”
“the rigors of boot camp”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for rigor come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.