isostasy
noun
isos·ta·sy ī-ˈsä-stə-sē 
1
: general equilibrium in the earth's crust maintained by a yielding flow of rock material beneath the surface under gravitative stress
2
: the quality or state of being subjected to equal pressure from every side
isostatic
ˌī-sə-ˈsta-tik
adjective isostatically
ˌī-sə-ˈsta-ti-k(ə-)lē
adverb 
Word History
Etymology
International Scientific Vocabulary is- + Greek -stasia condition of standing, from histanai to cause to stand — more at stand
First Known Use
1889, in the meaning defined at sense 1