pseudoword
unit of speech or text that appears to be an actual word in a certain language, while in fact it has no meaning in the lexicon
barbarous name
meaningless word used in magic rituals
nonsense word
unlike a sememe, may have no definition; if it can be pronounced according to a language's phonotactics, it is a pseudoword; used in literature for poetic or humorous effect. Proper names of real or fictional entities are sometimes nonsense words