n 1  :  pleurisy accompanied by pneumonia  2  :  a highly contagious pneumonia usu. associated with pleurisy of cattle, goats, and sheep that is caused by a microorganism of the genus Mycoplasma (esp. M. mycoides)  3  :  a contagious often fatal respiratory disease esp. of young pigs that is caused by a bacterium of the genus Haemophilus (H. pleuropneumoniae)  4  :  pleurisy of horses that is often accompanied by pneumonia and is caused by various microorganisms .
 
 
 
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