According to the Americans with Disabilities Act, a qualified individual with a disability is "an individual with a disability who, with or without reasonable modification to rules, policies, or practices, the removal of architectural, communication, or transportation barriers, or the provision of auxiliary aids and services, meets the essential eligibility requirements for the receipt of services or the participation in programs or activities provided by a public entity."
For more information, consult Glossary of Disability-Related Terms and/or the Americans with Disabilities Act.