I guess the answer is that the objects in a DOM really are objects, in that they have behaviors and methods. For example, multiple processing instructions can occur under an element. So the model is a tree of very low-level objects. It's a tree-structured hierarchy of objects that comprise a document. That's probably all you want for the glossary.
Short answer is yes.
By no means is the opaque internal implementation a document interchange format. I think the distinction is critically important. I hope this helps. The definition of a DOM escapes me. Thanks, I'll use that for the moment.