# Rigor
## Overview
**Rigor** (British spelling: **rigour**) describes the quality of strictness, thoroughness, or severity. It operates across intellectual ('academic rigor'), physical ('the rigors of winter'), medical ('rigor as a symptom'), and social ('de rigueur') contexts, all unified by the image of inflexible hardness.
## Etymology
From Latin *rigor* ('stiffness, numbness, hardness, coldness, severity'), from *rigere* ('to be stiff, to be numb with cold'), from PIE **\*h₃reyǵ-** ('to be rigid, stiff').
## Semantic Range
The Latin word *rigor* already covered the full semantic range that English inherited:
1. **Physical stiffness**: the body becoming hard and immovable 2. **Cold**: numbness from low temperature (rigere often meant 'to be frozen') 3. **Severity**: harshness of conditions, punishment, or judgment 4. **Exactness**: strict precision in method or argument
### Rigor Mortis Literally 'the stiffness of death' — the post-mortem rigidity caused by chemical changes in muscles. This is the most direct descendant of the Latin physical sense. Rigor mortis typically begins 2-4 hours after death, peaks at about 12 hours, and gradually resolves over 24-72 hours.
### The Rigors of Climate 'The rigors of winter' or 'the rigors of frontier life' preserve the coldness and harshness senses — conditions that numb, stiffen, and test endurance.
### Intellectual Rigor Academic and scientific rigor demands that methods be exacting, evidence be thoroughly examined, and reasoning be logically airtight. The metaphor maps physical unbendability onto intellectual standards: a rigorous argument is one that cannot be twisted or broken.
### Medical Rigor A **rigor** (or **chill**) in medicine is an episode of severe shivering during fever, caused by rapid temperature changes and muscle contraction. The patient becomes stiff and shakes uncontrollably — a direct physical manifestation of the Latin original.
## De Rigueur
The French phrase **de rigueur** ('of strictness') entered English to mean 'required by etiquette or fashion.' Something is de rigueur if social convention makes it mandatory — a black tie at a formal dinner, a specific dress code at an institution. The social sense extends the metaphor: propriety as an inflexible requirement that cannot be bent.
## Related Forms
The family includes **rigorous** (adjective), **rigorously** (adverb), **rigid** (adjective, from the same Latin root — completely stiff), **rigidity** (noun), and **rigor mortis** (medical/forensic term). British English spells it **rigour** for the noun but **rigorous** for the adjective.