What is the definition of: 'commodity space'? I have seen the concept of commodity space being used multiple times in economics, in particular within microeconomics, but I could not find a general definition of it.
Based on the examples that I have seen, I would guess that it is a vector-space of n-dimensions, in which every dimension coincides with one specific commodity. Furthermore, n is equivalent to the cardinality of the set of commodities.
Is this understanding correct? Is there even a universal understanding of a commodity space?
Yes, a commodity space is the set of all possible commodity bundles. The simplest Micro 101 example is typically the nonnegative quadrant of $\mathbb{R}^2$, but in general equilibrium theory it is often assumed to be infinite-dimensional since there are infinitely many commodities (each good is differentiated by time and space, etc.).