“I don’t give a damn for a man that can only spell a word one way.” – Mark Twain
A lot of words came from writers, like Shakespeare who simply made them up.
In writing fantasy, it is obvious that one might have to create words for things that don’t exist, and then explain them. Combine with the fact that each culture, and subculture, is different, and will have different expressions for things. For example, Americans and British speak English. The words are the same, but they don’t always mean the same thing.
In my own writing, I’ve focused a bit on Susurrus’ gambling, particularly dice. I made up a game with the aspect that a fate die changes the results of the “combat” dice. Then I created references to this aspect, i.e. when the “fate die is cast”, or fate has cast her die. I could even add “fate changed the roll” or other references. It adds just that little bit of “authenticity” without being to foreign.