Here is a terminology guide:

Put the person before the disability. For example, use "people with disabilities" as opposed to "disabled people" or "the disabled."

Do not use phrases such as "confined to a wheelchair," "crippled," "afflicted," "victim of" or "suffers from a disorder." These references diminish dignity and magnify the disability. Instead, refer to "the person who uses a wheelchair" or "the person with an emotional disorder."

Avoid portraying people with disabilities as superhuman, courageous, poor or unfortunate. People with disabilities do not want to be, nor should they be, measured against a separate set of expectations.

Avoid using trendy euphemisms to describe people with disabilities. Expressions such as "physically challenged," "special" and "handi-capable" are generally regarded by people with disabilities as patronizing.

It is probably unnecessary in speaking, writing, producing audio or video tapes, or in promoting products to mention a person's disability. If the disability is not relevant, leave it out. If a person's disability is relevant to an issue, distinguish between impairment, disability and handicap.

Impairment is used to characterize a physical, mental or physiological loss, abnormality or injury that causes a limitation in one or more major life functions. For example, "The loss of her right leg impaired her ability to walk long distances."

Disability refers to a limitation that affects an individual's ability to perform certain functions. For example, it is correct to say, "Blindness is a disability that prevents one from driving a car."

Handicap describes a barrier or problem created by society or the environment. For example, "People with disabilities are sometimes handicapped by the assumption of employers that their abilities are somehow limited."
When it is necessary to refer to a person's disability, use the following list as a guide:

Deaf refers to profound hearing loss in a person who does not have the ability to discriminate speech aurally. Hard of hearing may be used to describe any degree of hearing loss. Never refer to a person as being "hearing impaired," "deaf mute" or "deaf and dumb."

Blind most frequently is used to describe severe vision loss. Either blind or visually impaired are acceptable terms to describe all degrees of vision loss.

Developmental disability is any severe mental and/or physical disorder that began before age 22 and continues indefinitely. Individuals with mental retardation, autism, cerebral palsy, epilepsy and other similar long-term disabilities may be considered to have developmental disabilities.

Mental illness is a term describing many forms of illness, such as schizophrenia, depression and emotional disorders. Clinical terms such as "neurotic" and "psychotic" should be used only for clinical writing. Never use the terms "demented," "insane," "abnormal," "deranged," "deviant" or "mad." It is preferred to use the term "person with a mental disability" when referring to a person with any form of mental illness.

Do not use "normal," "able-bodied," or "healthy" to describe people without a disability, as these words imply a person with a disability isn't normal or healthy.

(Definitions and terminology courtesy of The President's Committee on Employment of People with Disabilities and Gailaudet University)

The Americans with Disabilities Act (ADA) has a three-part definition of "disability." Under the ADA, an individual with a disability is defined as a person who has:

a physical or mental impairment that substantially limits one or more major life activities;

a record of such an impairment; or is regarded as having such an impairment.

An impairment under the ADA is a physiological or mental disorder.

To be a disability covered by the ADA, an impairment must substantially limit one or more major life activities. These are activities that an average person can perform with little or no difficulty. Examples are:

walking

seeing

speaking

hearing

breathing

learning

performing manual tasks

caring for oneself

working

These are examples only. Other activities such as sitting, standing, lifting, or reading are also major life activities.