Our oldest daughter had a barking cough last night, and her mother (the ICU nurse) immediately recognized it as false croup. Always thought it was weird to call it “false”, so I looked it up (after the coughing stopped).
According to Wikipedia, the early modern English verb to “croup” means “to cry hoarsely”. “Real” croup is caused by a diphtheria infection. False, or viral, croup produces a similar cough, but is not diphtheric, so the French called it “faux-croup” to tell them apart, and then the “false” bit just carried over with translation.