Word for a misused word
Perhaps malapropism?
The mistaken use of a word in place of a similar-sounding one, often with unintentionally amusing effect, as in, for example, “dance a flamingo” (instead of flamenco).
Also eggcorn
a word or phrase that results from a mishearing or misinterpretation of another, an element of the original being substituted for one that sounds very similar or identical (e.g. tow the line instead of toe the line ).
How about "catachresis?"
catachresis: the incorrect use of words, as luxuriant for luxurious.