Post/Author/DateTime	Post
#1 Stormborn20 Apr 12, 2015 19:27:35	In 5th edition, Deep Speech and Undercommon are listed distinct languages (PHB 123). Given that the typical speakers of Deep Speech are listed as mind flayers and beholders I figured that it is the language of the Far Plane. But when I searched for details online it appears that they are the same language... ?   http://forgottenrealms.wikia.com/wiki/Deep_Speech
#2 AaronOfBarbaria Apr 12, 2015 20:29:57	Deep Speech is a language that originates in some other realm, much like mind flayers and beholders do. It's more along the lines of the language of the Great Old Ones than a language native to the material plane in any way.   Undercommon is just the common language of the underdark, and is likely made up of various borrowed words and phrases from the other languages spoken in the underdark, but then polluted by mispronunciation or misuse enough to become a distinctly separate langauge (like how English is mish-mashed bits of various other languages when you get to the root of the language).
#3 SpedGuy Apr 13, 2015 20:12:16	Yeah undercommon is the 'trade language' of the underdark; probably with drow, svirfneblin, derro/deuregar, kobold, Kuo-tuo, and yes even deepspeech components in it.     Older editions also had undersea common, spelljammer common, and planar cant filling similar roles.  Common itself was also explicitly a pidgin/trade tongue with humans speaking their own language(s)   Deep-Speech is a new invention trying to aggregate the 'weird abberation' languages into one grouping; except Grell who seemed to have kept their old language in the MM
#4 delroland Apr 15, 2015 21:44:26	I imagine Undercommon to be pig Latin, while Deep Speech is all, "Iä! Iä!"