diarrhea vs looseness of the bowels

diarrhea

noun
  • A gastrointestinal disorder characterized by frequent and very soft or watery bowel movements. 

  • The watery or very soft excrement that comes from such bowel movements. 

looseness of the bowels

How often have the words diarrhea and looseness of the bowels occurred in a corpus of books? (source: Google Ngram Viewer )