Causing a boom, maybe (10)
I believe the answer is:
supersonic
(Other definitions for supersonic that I've seen before include "Faster than the speed of sound" , "Very fast - 11 (anag)" , "moving very fast" , "Faster than Mach 1" .)
I believe the answer is:
supersonic
(Other definitions for supersonic that I've seen before include "Faster than the speed of sound" , "Very fast - 11 (anag)" , "moving very fast" , "Faster than Mach 1" .)