en·sta·tite (ěn'stə-tīt') n. A glassy, usually yellowish gray variety of orthorhombic pyroxene having a magnesium silicate base, mainly MgSiO3, usually found embedded in igneous rocks and meteorites.
[Greek enstatēs, adversary (because of its refractory quality) : en-, in, at, near; see en-2 + -statēs, one that stands; see stā- in Indo-European roots + -ite1.]