noun

1. harshness or severity; specif.,
   1. strictness or inflexibility the rigor of martial law
   2. extreme hardship or difficulty the rigors of life
   3. inclemency, as of weather
2. exactness in precision or accuracy; exactitude
3. a severe, harsh, or oppressive act, etc.
4. stiffness; rigidity; specif., a condition of rigidity in body tissues or organs, in which there is no response to stimuli
5. a shivering or trembling, as in the chill preceding a fever

Etymology: ME < MFr rigueur < L rigor < rigere: see rigid