The word croup comes from the Early Modern English verb croup , meaning "to cry hoarsely"; the name was first applied to the disease in Scotland and popularized in the 18th century.  Diphtheritic croup has been known since the time of Homer 's Ancient Greece and it was not until 1826 that viral croup was differentiated from croup due to diphtheria by Bretonneau .   Viral croup was then called "faux-croup" by the French and often called "false croup" in English,   as "croup" or "true croup" then most often referred to the disease caused by the diphtheria bacterium .   False croup has also been known as pseudo croup or spasmodic croup.  Croup due to diphtheria has become nearly unknown in affluent countries in modern times due to the advent of effective immunization .