Definition of croup

• n. - The hinder part or buttocks of certain quadrupeds, especially of a horse; hence, the place behind the saddle.
• n. - An inflammatory affection of the larynx or trachea, accompanied by a hoarse, ringing cough and stridulous, difficult breathing; esp., such an affection when associated with the development of a false membrane in the air passages (also called membranous croup). See False croup, under False, and Diphtheria.