prints as the user-defined values and rules associated with symbol.

Definition does not print information for ReadProtected symbols. Definition uses InputForm to format values.

Definition of a rather evolved (though meaningless) symbol:

Some usage:

Its definition:

For ReadProtected symbols, Definition just prints attributes, default values and options:

This is the same for built-in symbols:

ReadProtected can be removed, unless the symbol is locked:

Clear clears values:

ClearAll clears everything:

If a symbol is not defined at all, Null is printed: