* A misspelling: It could be a misspelling of a word like "nuisance" or "nursy."
* A slang term: It could be a slang word or nickname used in a particular region or group.
* A made-up word: It could be a word invented for a specific purpose, like a character name in a story.
To understand the meaning of "nussie," you need more context. Please provide:
* The sentence or phrase it was used in.
* The speaker's background and location.
With more information, I might be able to determine the intended meaning.