Zettimah

Zettimah is equal to \(f_{\psi_{I(0,0)}(I(10^{21},0))}(10)\) using the fast-growing hierarchy with the fundamental sequences for the function collapsing \(\alpha\)-weakly inaccessible cardinals. The term was coined by wiki user Denis Maksudov.

Etymology
The 3 parts of the name, "zetto", "im" and "ah", mean \(10^{21}\), \(I(\alpha,0)\)-cardinals and the function collapsing \(\alpha\)-weakly inaccessible cardinals \(\psi_{I(0,0)}\) respectively, which form \(\psi_{I(0,0)}(I(10^{21},0))\) when concatenated backwards (where "zetto" and "im" form \(I(10^{21},0)\) - the first \(10^{21}\)-weakly inaccessible cardinal). So the full name indicates the ordinal index of the number.