We can differentiate between objects by two axii, their form, which is the shape they take, and their "thingness." Thingness refers to the reason for an object, its purpose that it is supposed to achieve. For example, the thingness of a guitar is to make music. We can differentiate it from a similar object like a banjo, because while they share similar purposes, they have different shapes. We hold in our minds this thingness in the form of a Concept. If you were to show me a picture of a guitar, I would match that image (its form and thingness) to my Concept of guitar, and so I could recognize that object.
Now if we have a guitar, but remove the strings by this framework we could say that it is no longer a guitar, because while it has a shape of a guitar, it now lacks the "thingness" of a guitar, that is it can no longer be used to make music. So its new label becomes "an object that's almost a guitar."
Another example. We have a Bic lighter. A lighter is used to light things. What if it runs out of fluid? since it can no longer fulfill its purpose to create fire, it shouldn't be considered a lighter, we should say "that used to be a lighter." Furthermore, a Bic lighter can also be used as a bottle opener. So when a lighter runs out of fluid, it is no longer a lighter but can still be used as a bottle opener. Therefore, the object is now only properly referred to as a bottle opener.
I consider this simply a different way of looking at the things, so it's not something that I feel is provable. Is this a flawed perspective? If it isn't, is it possible to create a way of proving this works?