1. Definition and Symptoms of Diarrhea Diarrhea refers to an increase in the number of bowel movements per day, an increase in the volume of stools, thin or watery texture, and is accompanied by uncomfortable symptoms such as abdominal bloating and abdominal pain. The main symptoms of diarrhea in 11-month-old babies are frequent defecation, watery or yellow and soft stools, which may be accompanied by nausea, vomiting and other symptoms. 2. Causes of diarrhea in 11-month-old babies There are many causes of diarrhea in 11-month-old babies.