Americans with Disabilities Act

Section 504 Compliance Handbook and ADA define disability as (1) a physical or mental impairment that substantially limits one or more of the major life activities; (2) a record of such an impairment; or (3) being regarded as having such an impairment. 

The guidance observes that the definition of disability under the ADA and Section 504 might differ from the definition of disability under other laws, such as the Vietnam Era Veterans Readjustment Assistance Act.