WordWeb Online

1. The quality of being hard to endure, uninviting or formidable
   "the rigour of northern winters";
   - asperity, grimness, hardship, rigor [US], severity, severeness, rigorousness, rigourousness [Brit, non-standard]
    
2. The quality of being valid and rigorous
   - cogency, validity, rigor [US]
    
3. Excessive sternness
   "the rigours of boot camp"; "rigour of character";
   - severity, severeness, harshness, rigor [US], rigorousness, rigourousness [Brit, non-standard], inclemency, hardness, stiffness

Sounds like: rigger

Derived forms: rigours

Type of: believability, credibility, credibleness, difficultness, difficulty, sternness, strictness

Encyclopedia: Rigour