rigor mortis

UK: /ˌrɪgə^rˈmɔː^rtɪs/

US: /ˈrɪgˈɚ ˈmɔrtɪs/

US: (rig′ər môr′tis, or, esp. Brit., rī′gôr)

WordReference Random House Learner's Dictionary of American English © 2025

rig•or mor•tis /ˈrɪgˈɚ ˈmɔrtɪs/  n. [uncountable]

1. Physiology the stiffening of the body after death.

WordReference Random House Unabridged Dictionary of American English © 2025

rig•or mor•tis  (rig′ər môr′tis, or, esp. Brit., rī′gôr), 

1. Physiology the stiffening of the body after death.

• Latin: literally, stiffness of death
• 1830–40

Collins Concise English Dictionary © HarperCollins Publishers::

rigor mortis / ˈrɪɡə ˈmɔːtɪs/ noun

1. the stiffness of joints and muscular rigidity of a dead body, caused by depletion of ATP in the tissues. It begins two to four hours after death and lasts up to about four days, after which the muscles and joints relax

Etymology: 19th Century: Latin, literally: rigidity of death