Aviation Dictionary
موج ضربه ای پیشرو ،موجی که پیشاپیش جسم متحرک ولی به آن نچسبیده در حرکت باشد
A detached shock wave (also called a bow shockwave), it's a shock wave which forms when an aircraft is flying at a speed faster than the speed of sound, a speed greater than Mach one. A detatched wave either forms immediately ahead of the aircraft or is attached to the nose of the aircraft.