Coframe
In mathematics, a coframe or coframe field on a smooth manifold  is a system of one-forms or covectors which form a basis of the cotangent bundle at every point. In the exterior algebra of , one has a natural map from , given by . If  is  dimensional a coframe is given by a section  of  such that . The inverse image under  of the complement of the zero section of  forms a  principal bundle over , which is called the coframe bundle. References

See also 

 Frame fields in general relativity
 Moving frame

Differential geometry