The World Health Organization defines "disability" as an umbrella term, covering impairments, activity limitations, and activity restrictions. An impairment is a problem in the body function or structure; an activity limitation is a difficulty encountered by an individual in executing a task or action; while participation restriction is a problem experienced by an individual in involvement in life situations.
Disability is thus not just a health problem. It is a complex phenomenon, reflecting the interaction between features of a person's body and features of the society in which he or she lives."
One need only consider the simple telephone to demonstrate this interaction. To an individual with hearing impairment, one would consider TTY devices or amplifiers to remove barriers; to an visually impaired person, one would consider talking or voice activated phones. An individual with physical or mobility issues may require a cell phone to keep on his or her person at all times, while a person with cognitive impairment that affects memory, may require a corded phone, attached to the wall, and not readily lost or forgotten.
In each of these cases, or complex phenomena, the individual has a barrier whose removal can be facilitated, and the reflection of interaction between a person's body, and the features of society within which he or she lives, can be enhanced to facilitate full inclusion.
Therefore, in considering the definition of Disabilty, one must always respect the concept of access or inclusion.