Constipation (also known as costiveness or dyschezia) refers to bowel movements that are infrequent or hard to pass. Constipation is a common cause of painful defecation. Severe constipation includes obstipation (failure to pass stools or gas) and fecal impaction, which can progress to bowel obstruction and become life-threatening. Constipation is a symptom with many causes. These causes are of two types: obstructed defecation and colonic slow transit (or hypomobility).