bow shock

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A shock wave produced when a moving object emits particles or waves into the medium through which it is moving.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun fluid dynamics a shock wave formed by the bow of an object travelling at supersonic speed
• noun astronomy the region of the magnetosphere in which the solar wind slows from supersonic to subsonic
• noun bow wave