Is there a linguistic term for 'made-up' word?

I believe the word you're looking for is "cromulent". It was used to describe the made up word "embiggens"

The closest match is, 'Undefined'.

Well, the problem with that is that any made-up word is no more and no less still, a word and this is because all words were made up by someone at some point (mostly Shakespeare and the Greeks, but many other people too).

What I think you are getting at is whether its defined in a dictionary or not. Seeing as you asked the question in English, the English dictionary in particular. This depends on whether the word is accepted by the people that govern the english language at Oxford University.

So, if this is what you mean then you could say that you invented a new word, that the word isn't defined in the Dictionary or it might be simpler to describe the word as 'undefined'.

(Edit) Someone above suggested 'neologism'. That's the best answer, I reckon.

The word you are looking for is 'nonce'. Nonce words are words that are created (or coined - hence coinage) either for some particular communication purpose or in linguistic experiments. In these experiments, nonce words may either follow the morphology of a language (rules of normal formation of words) or break them on purpose. One of the most famous nonce experiment involves investigating children's ability to correctly form the plural of the nonce word 'wug' (add an -s that's pronounced like [z]...

you hit upon a sparkling Bertie Bott's Jelly Bean, what's it made up of ?? Vanilla with little products of chocolate and that's frosty chilly like an ice-cream! call right here unnamed gadgets contained in the books: The potion Dumbledore drank contained in the cave ??[HBP]=stay poison The curse Dolohov used on Hermione ??[OoTP]=Bretfingus! The snake species the position Nagini is from=Black and venomous you in uncomplicated words received the Wizard-Lottery, the grand prize is infinite monetary help for any project. What might want to you do ??[you could't take the money except you do some thing useful with it, in accordance for your guidelines for sure(it would want to be some thing even if that's solid or undesirable)] make investments in a project that can assist make wands for muggles(because i choose one)! Honeydukes are operating short on recommendations, make up a sparkling sweet take care of for the keep ?? Manilla(Mango and Vanilla creamy sweet with chocolate crumbles) Your wizard buddy is keen to ease your existence by making use of making one chore do itself, what chore might want to you search for help in ?? interpreting!!!

The only thing I can think of is "fabricated"

The word was fabricated in the mind of the speaker

Portmanteau?

Neologism means a new word.

psuedo?

a fictive statment?

an invented holler?