Deep Speech

Deep Speech, also known as Undercommon, is a trade language spoken by the majority of intelligent races native to the Underdark. Speakers of Undercommon include the aboleth, choker, chuul, cloaker, delver, drider, drow, Duergar duergar, dwarf, githyanki, githzerai, grimlock, kobold, kuo-toa, orc, rakshasa, roper, svirfneblin and mind flayer races.
Undercommon is written using the Espruar alphabet.