irritable bowel syndrome

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A chronic disorder characterized by motor abnormalities of the small and large intestines, causing variable symptoms including cramping, abdominal pain, constipation, and diarrhea.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun pathology A functional disorder causing the nerves and muscles of the large intestine to be oversensitive, leading to symptoms such as cramp, bloating, flatulence, diarrhoea and constipation.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun recurrent abdominal pain and diarrhea (often alternating with periods of constipation); often associated with emotional stress