supercritical

UK: /ˌsuːpəˈkrɪtɪk^əl/ US: (so̅o̅′pər krit′i kəl)

WordReference Random House Unabridged Dictionary of American English © 2026

su•per•crit•i•cal  (so̅o̅′pər krit′i kəl), adj. 

1. extremely critical.
2. Physics pertaining to a mass of radioactive material in which the rate of a chain reaction increases with time.

• super- + critical 1600–10

su′per•crit′i•cal•ly, adv. 
su′per•crit′i•cal•ness, n. 

Collins Concise English Dictionary © HarperCollins Publishers::

supercritical / ˌsuːpəˈkrɪtɪk^əl/ adjective

1. (of a fluid) brought to a temperature and pressure higher than its critical temperature and pressure, so that its physical and chemical properties change
2. of or containing more than the critical mass