what's detwinning

Now I am doing some work about nanotwinned copper, and don't understand what's the nature of "detwinning". 

Could any disappearance of the original nanotwin structure and the formation of a single grain or a new twin structure with TBs in a different orientation and/or with different TB spacing be called detwinning?

To my limited understanding, this term more often appeares in shape memory alloy. Detwinning in crystalline solids is a unique
deformation mechanism partially responsible for the shape memory effect. Different from dislocation mediated plastic
deformation, detwinning does not introduce “permanent” structure change to the
material rather than introducing merely “inelastic” deformation with atoms
migrate less than an atomic distance and act synergistically. Thus, upon
reverse phase transformation, the deformation associated with detwinning will
be recovered and without new grain formation.  

Does the defination or conception change with the metal system? Thanks