Tethracross

The tethrasquare (also called tethracross) is equal to E100#^^##100 in Extended Cascading-E Notation, which expands to E100#^^#>#^^#>#^^#> ... ... >#^^#>#^^#>#^^#100 with 100 #^^#s. The term was coined by Sbiis Saibian.

Etymology
The name of this number is based on the number tethrathoth and the word "square".