What is a non-word called...what word is defined as so?

I don't want to call a non-word a non-word. I vaguely remember hearing a definition that was possibly defined more of an utterence or more of a shreak. I am thinking of something more along the lines of a nonword such as "joboheadskunk" as it uses actual letters and can be pronounced in it's own way but is still not an actual word. Even related words would help, I just can't brainstorm anything useful for a thesaurus.

It's not slang as slang is more of informal speech yet makes sense by those who use it and thus implies a minimal level of comprehendable intelligence by those using it (though not suggesting an always low intelligence of users).

It's not a neologism as that seems to be defined as a new word being logically constructed.