* Could be a misspelling: It may be a variant of a similar name, like "Tiona" or "Tiana," both of which are variations of "Diana," meaning "divine" or "goddess."
* Could be a unique name: Many people choose unique names for their children. It's possible "Tionna" is a name created by parents.
* Could be a specific term in a certain field: Without more context, it's impossible to say if it has a meaning in a specific field like science, literature, or a particular language.
To get a definitive answer, you'll need to provide more context about where you encountered the word "Tionna."