* It's a misspelling: There might be a similar-sounding word that you're thinking of. Could you provide more context about where you encountered this word?
* It's a regional term: The word could be specific to a particular dialect or region. If you know where you heard it, that might help identify its origin.
* It's a made-up word: It could be a fictional word created for a story, game, or other creative work.
Please provide more information so I can help you understand the origin of the word "nishnabotna".