Undercommon

Undercommon is the language spoken within the Underdark. It has roots in the Common tongue but is harsher, sharper and more bitter. It's words are contorted and have greater influences of the Drow subdialects of Elvish and the Duregar subdialect of Dwarven.
Undercommon uses a hybrid of the Elvish and Dwarven script that removes the more distinct elements of both. It is a rushed script that uses a lot of shorthand making its understanding by others often either imeedeately clear through context or requiring time to decipher the origin of its lettering.