Is there a word for deeper, more abstract, layer of truth? In computer science, we have this term called abstraction layer that refers to different level of abstractions, and I was wondering if in metaphysics there were similar terms or concepts used to refer to what might be underneath the material world we perceive. I am not talking of scale, molecule scale, atomic scale, quantum scale, etc, but different level of reality itself, something more abstract or deeper than the material world where molecules, atoms and quantum particles reside.
"...what might be underneath the material world we perceive"?
In Heidegger's terminology, the word you are look for actually is 'truth'. In contrast, the appearance of the world is Aletheia :-
Heidegger ... wrote that "Aletheia, disclosure regarded as the opening of presence, is not yet truth. Is aletheia then less than truth? Or is it more because it first grants truth as adequatio and certitudo, because there can be no presence and presenting outside of the realm of the opening?"