Let's talk about making up words. I see this done most commonly as an interjection/sound effect or in otherwise humorous/unserious way. In A Visitor for Bear, Bear stoppers up the chimney and Mouse asks that he unstopper it. Stopper is certainly not a verb but it is a funny usage because it is used three times, each a little longer and the meaning is obvious. In a PB WIP, I'm debating whether to use the word "stumblesome" as a modifier of a slope, rather than something like "stumbled down the slope". The tone is more lyrical and not humorous in this part, so I'm wondering if the novel word would be too jarring or off-putting. I'm also wondering if it would be a reason for my MS to be tossed on the slush pile because it was written by some rube that doesn't own a dictionary.