Anisotropic

adj. having different physical properties at different levels of measurement (Physics)

Anisotropy (pronounced with stress on the third syllable, ) is the property of being directionally dependent, as opposed to isotropy, which means homogeneity in all directions. It can be defined as a difference in a physical property (absorbance, refractive index, density, etc.) for some material when measured along different axes. An example is the light coming through a polarising lens.
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Adjective
1. not invariant with respect to direction; "anisotropic crystals"
(antonym) isotropic, isotropous
(similar) aeolotropic, eolotropic

(a.)
Not isotropic; having different properties in different directions; thus, crystals of the isometric system are optically isotropic, but all other crystals are anisotropic.
  

Pertaining to a material whose electrical or optical properties vary with (a) the direction of propagation of a traveling wave or with (b) different polarizations of a traveling wave. Note 1: Anisotropy is exhibited by non-cubic crystals, which have different refractive indices for lightwaves propagating in different directions or with different polarizations. Note 2: Anisotropy may be induced in certain materials under mechanical strain.