biaxial

Having two axes.

Having two axes of rotation and two planes of symmetry (e.g. having the shape of a spheroid)

Along two axes; e.g. in engineering, a shear or compression text of a material along two axes

mapping the shape of the Earth onto a biaxial ellipsoid

Having a value in two perpendicular directions. (In solid mechanics, it generally means that normal stresses exist in two of the possible three directions, though not necessarily equal in sign or magnitude.)