So in your fictional world, how does the main language work? How many languages are there in the setting you've created? Do the different species all have their own dialects? Are there words that mean something entirely different depending on who your character is speaking to and how are misunderstandings avoided or put right? Do any of your characters deliberately try to exploit misunderstandings in language for their own ends?
Just as we have had tyrants who deliberately use/misuse words/language to come to power/consolidate their grip on power, I would expect this to be reflected in fiction. How does your tyrannical character(s) use words to help them achieve their aims? What happens to those who use words to criticize them? Are people free to use words in print to produce political leaflets etc or is this all strictly controlled by the ruling party?
Words are vital. So who controls them in your setting? If they're not controlled at all, what happens to those who abuse free speech? If they are controlled, what happens to those who defy that control? One of my country's most important documents is the Magna Carta. What important documents exist in your fictional setting and who drew up those important words and why?