Wiktionary
n. A neologised word that does not have a given meaning.
Wikipedia
A nonsense word, unlike a sememe, may have no definition. Nonsense words can be classified depending on their orthographic and phonetic similarity with (meaningful) words. If it can be pronounced according to a language's phonotactics, it is a pseudoword. Nonsense words are used in literature for poetic or humorous effect. Proper names of real or fictional entities are sometimes nonsense words.
A stunt word is a nonsense word used for a special effect, or to attract attention, as part of a performance. Such words are a feature of the work of Dr. Seuss ("Sometimes I am quite certain there's a Jertain in the curtain").
The ability to infer the (hypothetical) meaning of a nonsense word from context is used to test for brain damage.
Usage examples of "nonsense word".
That was the third time the machine had said the same nonsense word.
He speaks this nonsense word in a perfectly clear, perfectly flat midwestern accent.
She will say a nonsense word when she means to say something quite different.
And see, they have discovered this green creature that was inside my tail rest--which they call by the interesting nonsense word, hassock.
And see, they have discovered this green creature that was inside my tail rest-which they call by the interesting nonsense word, 'hassock.
And see, they have discovered this green creature that was inside my tail rest--which they call by the interesting nonsense word, ‘.
Goldfarb said, pointing to the nonsense word formed by part of one row of letters.
I regarded it as a nonsense word for the nonce and not something likely to survive and be used years from now by a spaceman like Perry Rhodan.