But he DOES define it (vaguely). I have shown a little of this in the OP. There are other instances. What I am saying is they do not come together to form a worthy tool.
I can define "Burning Ghost", is it not difficult. I work with people everyday and have to explicate many words. I do so by example, synonym and binding of other terms. If someone were to ask what does "the" mean I'd have to explain how it is used, that is its "definition"; how it is put to use.
If that is true then it is extended on by way of language because of phenomenal experience. Heidegger was doing phenomenology of a certain breed.The question of being is not limited to phenomenal experience.
Heidegger's approach is hermeneutic.It seems to me that with your demand for a definition it is you who misunderstands the problem of being as one of language only.