property of surfaces in Euclidean space measuring whether or not it is possible to make a consistent choice of surface normal vector at every point

In the Euclidean space, R3 is called orientable if a two-dimensional figure (for example, ) cannot be moved around the surface and back to where it started so that it looks like its own mirror image (). Otherwise the surface is non-orientable. A concept connected to this is chirality. This means that no matter what, a human right hand, cannot be rotated in such a way that it becomes a human left hand. The right hand is therefore orientable.