Synonyms for Croup (same or very similar meaning)
WordNet sense 1 (a disease of infants and young children; harsh coughing and hoarseness and fever and difficult breathing):
spasmodic laryngitisWordNet sense 2 (the part of a quadruped that corresponds to the human buttocks):
hindquarters, rump, croupeFrom the ODE community, based on WordNetadd/edit