rig·or / ˈrigər/ • n. 1. the quality of being extremely thorough, exhaustive, or accurate: his analysis is lacking in rigor. ∎  severity or strictness: the full rigor of the law. ∎  (rigors) demanding, difficult, or extreme conditions: the rigors of a harsh winter.2. Med. a sudden feeling of cold with shivering accompanied by a rise in temperature, often with copious sweating, esp. at the onset or height of a fever. ∎ short for rigor mortis.

rigor (ry-ger) n. an abrupt attack of shivering and a sensation of coldness, accompanied by a rapid rise in body temperature. This often marks the onset of a fever and may be followed by a feeling of heat, with copious sweating. r. mortis the stiffening of a body that occurs within some eight hours of death in temperate climates, due to chemical changes in muscle tissue. It usually starts to disappear after about 24 hours.