Nursing report today included the note that the patient had not displayed any malappropriate behavior on 3-11 shift. (Notable because 7-3 had been hellish.)
Someone was trying to get fancier than "inappropriate," a favored word in informal mental health discussions. Maladaptive was probably lurking in the background at the creation of this neologism.
But it is one of those beautifully self-reflexive words. Malaprop comes from mal-apropos, "not fitting," or "ill-suited." So malappropriate is a malaprop.
BTW, a theater professor once told me that Shakespeare's Dogberry used malaprops before Sheridan's Mrs. Malaprop. I just looked it up and it is so. Decades earlier.