body wave

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

• noun A seismic wave that travels through the earth rather than across its surface. Body waves usually have smaller amplitudes and shorter wavelengths than surface waves and travel at higher speeds.

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

• noun geology A seismic wave that travels through the earth's interior rather than over the surface. P-waves and S-waves are examples of body waves.