Gigintar

Gigintar is equal to \(f_{\underbrace{C(C(\cdots(C(C(\Omega_{10^{18}}2,0),0),\cdots ),0)}_{999,999,999\text{-intar C's}}}(999,999,999\text{-intar})\) using the fast-growing hierarchy with fundamental sequences for Taranovsky notation. The term was coined by wiki user Denis Maksudov.

Etymology
The 3 parts of the name, "giga", "in" and "tar", mean \(10^{9}\) and Tar function (from Taranovsky's notation) respectively, which form \(Tar(10^{24})\) when concatenated backwards. So the full name indicates how the number is constructed.