Definition: "...the words that are used with a certain word or phrase and that help to explain its meaning."
"Context." Merriam-Webster.com. Accessed July 5, 2015. http://www.merriam-webster.com/dictionary/context
In terms of fiction, we can look at it like this: If you need to use a little-known or made-up word, it's important that you cushion that section with hints to help your readers discern its meaning. Simple, right?
Let's take that a step further with an example from the opposite end of the spectrum. Here, someone has replaced every instance of the verb "count" with a censor beep. No other words were changed, yet somehow, that beep informs our understanding and changes the context in which we would normally listen to a Sesame Street song...
Get your mind out of the gutter. :P
If someone were to cross out your little-known or made-up word, would they arrive at the contextual conclusion you intended? Something to think about!