Stretching, bending or compressing an object is called distortion. There are two kinds. In elastic distortion the object returns to its original shape and size when the forces are removed. Springs, rubber bands and the strings of a bow all do this when the forces are small enough.
In inelastic distortion the object does not return to its original shape when the forces are removed. It is permanently deformed. A paper clip that is bent and stays bent has been distorted inelastically, and so has a lump of modelling clay that has been squashed.
The same object can show both kinds. A spring stretched by a small force goes back to its original length. If it is stretched by a very large force it can be permanently longer, so it has changed from elastic to inelastic distortion.