Synonyms for rigor Found 14 synonyms across 3 meanings for “rigor”. something hard to endure (noun) asperitygrimnesshardshiprigourseverityseverenessrigorousnessrigourousness the quality of being valid and rigorous (noun) cogencyvalidity excessive sternness (noun) harshnessinclemencyhardnessstiffness Explore Related Words Rhymes with rigorSynonyms for asperitySynonyms for grimnessSynonyms for hardshipSynonyms for rigourSynonyms for severity Synonym Finder | Rhyme Finder | Poetry Editor