supercritical

Short definition from Wiktionary

Adjective

1. 1
   Of a substance or system above a critical threshold or range: Above its critical temperature and critical pressure.
2. 2
   Of a substance or system above a critical threshold or range: Having a mass sufficient to sustain an accelerating fission chain reaction.
3. 3
   Of a substance or system above a critical threshold or range: Above the speed of sound.