What is impairment?
impairment is Any loss or abnormality of psychological, physiological or anatomical structure or function. It is concerned with abnormalities of body structure and appearance, organ or system resulting from any cause. In principle, impairments represent disturbances at the organ level.
source: A GLOSSARY OF TERMS FOR COMMUNITY HEALTH CARE AND SERVICES FOR OLDER PERSONS. World Health Organization, 2004.