In solid mechanics and elasticity, clinotropy (from Ancient Greek κλίνειν (klínein) 'to incline', and τροπή (tropḗ) 'twist') refers to the property of certain anisotropic materials where no two or more perpendicular planes of symmetry can be found, indicating that they typically possess less symmetry than orthotropic materials. A clinotropic material is a type of material exhibiting clinotropy, whose mechanical properties—such as stiffness or strength—depend on direction, but in a more complex way than in other directional materials. In particular, the material behaves differently when measured in directions that are not symmetric with respect to a certain plane. This makes them a special case of anisotropic materials, which are materials that do not behave the same in all directions.
Clinotropic materials are important in fields like geology, materials science, and engineering, where understanding how a material reacts to forces from different directions is crucial. Unlike orthotropic materials, which have distinct properties along three main perpendicular axes (like wood), clinotropic materials vary continuously in directions around a plane, leading to a more intricate mechanical behavior.