Material can also be used as a noun. I use it that way all the time in my engineering work. And the two words are synonyms. Check the following link, which lists them as synonyms.
http://www.thesaurus.com/browse/matter?s=t
You understand that in a context of our discussion, Material and Matter are adjective vs noun? When we are talking about material as a noun, we are generally talking about building blocks, which is likewise relevant and isn't inherently circular. One describes functional use, and the other describes a general label that we describe a certain property of observable objects. Matter, just like the "Universe" is not a thing. It's a concept. Concepts point to what we are talking about. Thus, "Material" is likewise a concept that describes certain attribute that we ascribe to visible universe we GENERALLY experience. The definition doesn't discount spiritual. It namely generalizes.
For example, if I gave you a black box and you'd have to shake it and figure out what's inside... all you could do is give some adjective properties that would describe that object. It has weight, it seems solid since it doesn't pass through walls. That's what the label of material is. It's not a comment on "all there is". It's a comment on things that we consistently experience as the label describes them.
For example, the label like "apple" as a fruit, doesn't exclude the possibilities there are other fruits

.
I think you are taking your semantic argument when it comes to definitions to an unwarranted level.
But this is not a semantic issue about how we use words. I was looking for a definition that wasn't circular, didn't exclude the possibility of the immaterial, and was testable. Mine is not the only definition of the material/immaterial. In fact, it isn't what you would find in your average dictionary. But I've never been given a different definition that suits the purposes of a conversation like this.
1) See the above
2) There's nothing inherently circular in giving labels to things. When I label something a yellow, I merely label a recognizable property. When we label something as "material", it's likewise a recognizable properly.
Defining "spiritual" as non-material, and material as "not spiritual"... that would be circular, because it doesn't give a clearly recognizable property of either.
If we're heading toward the use of my definition, let me introduce "fundamental" as a synonym for immaterial. Many are used to thinking of the immaterial as something that is non-existent, and that often causes problems. It makes my statements appear nonsensical. I only used the word "immaterial" to highlight the dichotomy with the material. Going forward, I'll call it fundamental to give it a "positive" sense.
Wouldn't the attribute of "theoretical" and "imaginary model" have to be squeezed in as a disclaimer?
My mom is a physics professor, my dad is a philosophy one... and you could imagine the table-side conversations they'd have.
The reason why physics turned away from "aetherial" concepts and more towards particle physics is precisely because aetherial concepts are very difficult to quantify and describe in a consistent framework that doesn't fall apart. Growing up I was fascinated by Tesla, and theoretical models of his followers that would describe "aether" in a very similar manner that you would describe "immaterial" as fundamental.
In that model, that immaterial "perfect liquid) has disturbances that spin into vortex pattern and form matter that then recombines into more complex patterns of vortexes that push that immaterial aether around much like a spinning wheel circulates water in some receptacle. Thus, we have electric current, we have matter and we have gravity... etc.
It's a very interesting model. The problem with this model is that there's no way to confirm that it's valid. We can whip up all sorts of imaginary models and "fundamental" stuff, but it actually has to show some congruence with what we observe. If it doesn't, then what's the point of it all? It's just an interesting concept.
+ If you give "spiritual" the idea of "fundamental", by implication you actually saying that material reality is made up of "spiritual fundamental one". Thus, you are merely equivocating here, or so it seems without actually demonstrating the a-priori assumption. You merely re-labeling physical and attempting to define "spiritual" and by extention "God" into being by making it synonymous and vague.
It is possible we could detect the fundamental with our senses. However, it is more likely we would need an instrument to aid our senses.
So you are speaking about this "spiritual fundamental" as a hypothesis, right?
It also depends upon if you are restricting the word "sense" to the typical seeing, hearing, smelling, and touching. We can "feel" things in many different ways - such as the sense of falling, the sense of sickness, the sense of fatigue, the sense of hunger.
Ok, that's where your logic completely breaks down as you seem to misunderstand how our nervous system works. Please look it up

. There's nothing mysterious there. It's all about electrical impulses traveling from our nerve endings when these are triggered by certain organ states.
We likewise have hormonal endocrine system that tends to signal and induce certain states of our organs that would be difficult via nervous system alone.
Please explain how is that in any way related of sensing something "fundamental immaterial".
Again, you are equivocating and re-labeling concepts and attempt to define something into existence.
Regardless, whatever the means, yes, it is possible for us to perceive the fundamental. How would we know it exists if we couldn't perceive it?
The question is not whether it's possible... but what such experience is like, and how is it different from hunger or a state of fear or stress, if you equivocate it with a "feeling"?
Likewise, "Possible" is generally an imaginary state. It's possible that I could win a lottery from the first try... but that's not the likely reality. Possibility doesn't dictate the scope of reality. It's merely a mental projection of "things that could be".