The Collaborative International Dictionary of English v.0.48:

geophysics \geophysics\ n.
   A branch of geology that uses physical principles to study
   the properties of the earth.

   Syn: geophysical science.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

geophysics
    n 1: geology that uses physical principles to study properties
         of the earth [syn: geophysics, geophysical science]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "geophysics":
   Newtonian physics, acoustics, aerophysics, applied physics,
   astrophysics, basic conductor physics, biophysics,
   chemical physics, cosmical geology, cryogenics, crystallography,
   cytophysics, dynamic geology, electron physics, electronics,
   electrophysics, geodesy, geodetics, geodynamics, geognosy,
   geographics, geography, geological chemistry,
   geological engineering, geology, geomorphogeny, geomorphology,
   geoscopy, geotectonic geology, historical geology, hydrogeology,
   macrophysics, mathematical physics, mechanics, medicophysics,
   microphysics, mineralogy, mining geology, natural philosophy,
   natural science, nuclear physics, optics, paleontological geology,
   pedology, philosophy, physic, physical chemistry,
   physical geography, physical geology, physical science,
   physicochemistry, physicomathematics, physics,
   physiographic geology, physiography, psychophysics,
   radiation physics, radionics, soil mechanics, soil science,
   solar physics, solid-state physics, statics, stereophysics,
   stratigraphic geology, stratigraphy, theoretical physics,
   thermodynamics, zoophysics