Tsuwm, I might get angrified. I doubt that I would get
angryfied. But your 'orignal sense' #1. brings up an interesting concept.
1. The amount of wine or other liquor by which a cask or bottle falls short of being quite full (originally the quantity required to make good the loss by leakage or absorption).
Now, the part in the parentheses restates the first section, in a rather significant way. Because the first section, which can stand alone, is actually a definition of
something that isn't there! It does not refer to
"the amount of space" or "the amount of gas"--it refers to something that is absent. Quite intriguing, when you think about it.