Definition and descriptions of Impairment, Disability and Handicap: WHO in 1980, draws a three fold distinction between the Impairment, Disability and Handicap.
Impairment is any loss or abnormality of psychological, physiological or anatomical structure or function.
Disability is any restriction or lack of ability to perform an activity in the manner or within the range considered normal for a human being. Disability is resulting from an impairment.
Handicap is a disadvantage for a given individual, that prevents the fulfillment of a role that is considered normal (depending on age, sex, social, culture factors) for that individual. Handicap is resulting from an impairment or disability.
⇒ WHO (World Health Organisation)