Anisotropy:

Anisotropy is the property of being directionally dependent, as opposed to isotropy, which implies homogeneity in all directions. It can be defined as a difference, when measured along different axis, in a material's physical property (absorbance, refractive index, density, etc.) An example of anisotropy is the light coming through a polarizer.

A chemical anisotropic filter, as used to filter particles, is a filter with increasingly smaller interstitial spaces in the direction of filtration so that the proximal regions filter out larger particles and distal regions increasingly remove smaller particles, resulting in greater flow-through and more efficient filtration.

In NMR spectroscopy, the orientation of nuclei with respect to the applied magnetic field determines their chemical shift. In this context, anisotropic systems refer to the electron distribution of molecules with abnormally high electron density, like the pi system of benzene. This abnormal electron density affects the applied magnetic field and causes the observed chemical shift to change.

In the field of computer graphics, an anisotropic surface will change in appearance as it is rotated about its geometric normal, as is the case with velvet.

Anisotropic filtering (AF) is a method of enhancing the image quality of textures on surfaces that are far away and steeply angled with respect to the point of view. Older techniques, such as bilinear and trilinear filtering don't take account of the angle a surface is viewed from, which can result in aliasing or blurring of textures. By reducing detail in one direction more than another, these effects can be reduced.

Most materials exhibit anisotropic behavior. An example would be the dependence of Young's modulus on the direction of load. Anisotropy in polycrystalline materials can also be due to certain texture patterns which are often produced during manufacturing of the material. In the case of rolling, "stringers" of texture are produced in the direction of rolling, which can lead to vastly different properties in the rolling and transverse directions. Some materials, such as wood and fibre-reinforced composites are very anisotropic, being much stronger along the grain/fibre than across it. Metals and alloys tend to be more isotropic, though they can sometimes exhibit significant anisotropic behaviour. This is especially important in processes such as deep-drawing.