hypersonic

Adjective

hypersonic (comparative more hypersonic, superlative most hypersonic)

1. Of a speed, equal to, or greater than, or capable of achieving, five times the speed of sound.
   • He said there was worry among intelligence and military officials that China or Russia could be experimenting with hypersonic technology.2021 June 3, Julian E. Barnes, Helene Cooper, “U.S. Finds No Evidence of Alien Technology in Flying Objects, but Can’t Rule It Out, Either”, in The New York Times, →ISSN, archived from the original...
2. Of a speed, far enough above the speed of sound as to cause significant differences in behaviour due to chemical reactions or dissociation of the air.