Is the cppreference definition of non-static data member wrong?

Question

Definition from cppreference:

Non-static data members are the variables that are declared in a member specification of a class.

And they have the example:

class S
{
   int& r;               // non-static data member of reference type
};

But we know that non-static data member references are not variables because of the Standard:

§3/6: A variable is introduced by the declaration of a reference other than a non-static data member or of an object.

So is their definition of non-static data member wrong (they forgot about this exception)? Where I can find correct definition of the term "non-static data member"?

Unfortunately I couldn't find a definition of non-static data member in the C++ Standard.

EDIT: From cppreference object definition and discussion below we can conclude that non-static data members are not objects at all. And cppreference non-static member page corrected the discussed definition at the moment.

Answer 1

So their definition of non-static data member is wrong

Yes, it was wrong to use the word "variable" in the introductory sentence of the data members page (and, as mentioned in the comment, it's a wiki, the discussion tabs on wiki pages get faster feedback).

The current standard wording is 3[basic]/6 and :

A variable is introduced by the declaration of a reference other than a non-static data member or of an object. The variable’s name, if any, denotes the reference or object.

So, reference data members are excluded explicitly, and to figure out the rest you need the definition of "object" from 1.8[intro.object]/1

An object is created by a definition (3.1), by a new-expression (5.3.4), when implicitly changing the active member of a union (9.3), or when a temporary object is created (4.4, 12.2).

And finally 3.1[basic.def]/2

A declaration is a definition unless ... it declares a non-inline static data member in a class definition (9.2, 9.2.3),

Although it may seem like the distinction between variables and data members is impractical language-lawyerism, it is actually important when understanding compiler diagnostics, at least in this case:

struct X {
    int m;
    void f() { auto l = [m](){ return m; }; }
};

gcc:

error: capture of non-variable 'X::m' 

clang:

error: 'm' in capture list does not name a variable

icc:

error: member "X::m" is not a variable