An inaccessible cardinal is a cardinal number which cannot be expressed in terms of a smaller number of smaller cardinals.
Inaccessible Cardinal
See also
Cardinal Number, Inaccessible Cardinals AxiomExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Inaccessible Cardinal." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/InaccessibleCardinal.html