In the context of this article that's just confusing the issue. "Type" is both well-defined and not the same as "type" in a Ruby context.

What is type in a Ruby context?

Usually in a Ruby context you'd refer to something like Fixnum or String as types when really that's their "class"

    irb(main):005:0> 3.class
    => Fixnum

Such a "type" doesn't have much to do with "types" as discussed when referring to static types. They're simply orthogonal concepts.

The result of the #class method does not _fully_ encapsulate an object's type (e.g. #extend, #define_singleton_method, etc may have been used to modify the object's type) but every Ruby expression does have a type in exactly the sense as used when talking about static typing; the only difference is when you can (in general) determine that type. The #class method is not orthogonal to type, it is merely incomplete.

Sure, but that's not really relevant. All of your "typing" occurs at runtime and thus is entwined in the language dynamics and not its statics.