Variables can't be overridden. They can be shadowed or hidden.
If you have a method it is possible to alter that method in a subclass: that is
overriding.
If you have a field and declare a local variable with the same name, that local variable
shadows the field and hides it. See the
Java Language Specification page 86. The original field remains unchanged, however, and can be found with the
this. syntax.
If you have a superclass variable and a subclass variable with the same name the subclass variable
hides the superclass variable. There is a little example
here in the JLS. Note that in that example the hiding and hidden variables are of different type, whereas overridden methods must have the same signature and just about the same return types and Exception declarations.
See also pages 162-163 of the JLS.