Constipation is a symptom, not a disease.
Most commonly, constipation is thought of as infrequent bowel movements, usually less than 3 stools per week.
However, people may have other complaints as well including: 
Straining with bowel movements
Excessive time needed to pass a bowel movement
Hard stools
Pain with bowel movements secondary to straining
Abdominal pain
Abdominal bloating.

the sensation of incomplete bowel evacuation.

The Rome III Criteria are a set of symptoms that help standardize the diagnosis of constipation in various age groups.
These criteria help physicians to better define constipation in a standardized manner.
Constipation is a symptom, not a disease. Most commonly, constipation is thought of as infrequent bowel movements, usually less than 3 stools per week. However, people may have other complaints as well including: 
Straining with bowel movements
Excessive time needed to pass a bowel movement
Hard stools
Pain with bowel movements secondary to straining
Abdominal pain
Abdominal bloating.
the sensation of incomplete bowel evacuation.
The Rome III Criteria are a set of symptoms that help standardize the diagnosis of constipation in various age groups. These criteria help physicians to better define constipation in a standardized manner.
Constipation