Ports and Pirates
Common – A near-universal trade language spoken in the known world.
Elven – Spoken by most who shares a bloodline to the elves.
Dwarven – Spoken by Dwarves
Gnome – Spoken by the men of Izmir
Undercommon – Spoken by the Empire
Halfling – a sub-language of Elven
Orc – Spoken by people in contact with the Oju Tribes
Sylvan – Used to speak to creatures of the Fey
Giant – Spoken by lumbering Giant-folk.
Treant – Perhaps the language of the earth, in the end you’re still talking to a tree.
Goblin – What’s worse than learning Goblin? Knowing that half of this already primitive language is just different ways to say “destroy”. Perhaps worse would be the thought you could honestly have a coherent conversation with a Goblin.
Celestial – Known mostly by religious men so the Gods may hear their calls.
Celestial Gods: Pelor, Bahamut, Mummu
Infernal – Known mostly by religious men so the Gods may hear their calls.
Infernal Gods: Lolth, Kord, Hanseath
Very Uncommon Languages
From the DM – Trying to know a Very Obscure Language means giving up the chance to know 2 other languages.
Aquan – Known mostly by foolish sailors in vain attempts to flirt with mermaids. Pirates seem to use it all the same.
Vegepygmy – Not so much a language, as more of a complex sequence of notes bards play to send messages to other bards.
Draconic – Oddly Spoken by Izmir Viziers when the Age of Dragons have been long gone.