Speed needs to be understood as a matter of displacement vectors. Technically speed is a vector of speed within all traditional degrees of freedom. Speed in the sense of versus debating is a three dimensional variable, because one can displace themselves across the x, y, and z axis.
Higher dimensional characters can displace themselves across different axes, for example a four dimensional character can move across the x,y,z
and w axes. When it comes to this, it isn't immeasurable in VSB transcendental terms I guess. This is higher dimensional travel or something, because technically they have a vector going in the w axis that is a given speed. It's just typical three dimensional characters cannot percieve or displace themselves in that distance. The higher dimensional displacement allows a higher dimensional being to move into places a person cannot perceive, and so it is in a sense immeasurable to the perspective of a person who basically just saw someone teleport. However it's not literal immeasurability, that being just moved a certain speed in a unperceivable direction.
Infinite speed is the idea that either you can go infinite distance in a set amount of time, or you can get to any distance in 0 seconds without teleportation. Infinite speed is dealing with the typical degrees of freedom - up, down, left, right, etc. Someone with infinite speed cannot displace time however. Someone with infinite speed across 4 dimensions is not literally immeasurable, they are just infinite on 4 dimensional levels.
However, higher spatial dimensions when unbound are typically larger. You can see this with nsphere volume/radius calculators. However, only an infinite dimensional structure would be infinitely larger. An infinite dimensional character will inherently have infinite speed due to how n-volume works, but otherwise it will just be (quantifiably) larger by a certain algorithmic amount.
What is immeasurable speed then? One needs to understand the difference between spatial dimensions x,y,z,w, etc and temporal dimensions t. Even with infinite speed, you can only displace across anywhere in space. Someone with immeasurable speed can, without specialized hax or relativistic loopholes, physically move across a temporal dimension. You can't calculate someone moving 5 meters in -5 seconds, or 5 meters in 4i seconds. It's immeasurable. That's traditional immeasurable speed. There is another, cardinal immeasurability.
Set theory is the idea that some infinities are larger than others, the set of natural numbers (1,2,3,4,5,6,...) is smaller than the set of all real numbers (Which includes irrational numbers) one is "countable" because you can get from 1 to 2 when counting natural numbers, the other is "inacessible" because you literally can't begin or end if you count uncountable numbers. This explains how fictional universes can do "Our infinity is larger than yours"
If someone is on a transcendentally larger layer that is uncountably infinite, suddenly they are moving at distances we cannot measure. They are immeasurable because they are working on an uncountably larger scale.
At a certain point, I think it's aleph-two? Dimensionality ceases entirely, speed becomes irrelevant because there is no such thing as displacement vectors on that level. What's shown in books or comics is simply transcendental analogues to displacement in terms we can understand. Godsphere is probably Aleph-Two level if we are to believe its ontological nature
@Sigismund might need to correct me here. I would wager the Super Spiral Universe is potentially on that level too? IDK
@Stocking Anarchy may know. As for Marvel, who is the expert there?
Inaccessibility is a specific level of cardinality beyond alephs. You can have aleph-aleph-aleph-... and never reach inaccessibility which is a very specific mathematical exploit to justify its existence. Realistically, nothing in fiction reaches inaccessibility unless autistically shown, or if they transends mathematics or some shit. Basically, inacessible shouldn't be a term
because nothing realistically reaches it We need better and more specific terms, but this is the gist.