Ableism: A system of superiority and discrimination that provides or denies resources, agency, and dignity based on one’s abilities (mental/intellectual, emotional, and/or physical.) Ableism depends on a binary, and benefits able-bodied people at the expense of disabled people. Like other forms of oppression, ableism operates on individual, institutional and cultural levels.
Accessibility: a general term for the degree of ease that something (e.g., device, service, physical environment and information) can be accessed, used and enjoyed by persons with disabilities. The term implies conscious planning, design and/or effort to make sure something is barrier-free to persons with disabilities. Accessibility also benefits the general population, by making things more usable and practical for everyone, including older people and families with small children.
Intellectual disability: also called a developmental disability, involves significant limitations both in intellectual functioning (reasoning, learning, problem solving) and in adaptive behavior, which covers a range of everyday social and practical skills. Some people may be born without this disability, but develop it later in life due to an illness or accident.
Impairment: a physical, sensory, intellectual, learning or medical condition, including mental illness, that limits functioning and/or requires accommodation. Impairment may be apparent to others or hidden, inherited, self-inflicted or acquired, and may exist alone or in combination with other impairments. Impairment can affect anyone (whatever their gender, sex, race, culture, age, religion, creed, etc.).
Anti-Violence Project. Glossary. University of Victoria.
Ontario Human Rights Commission. Glossary of human rights terms.
Disability and Equity at Work by 
Abilities, Opportunities and the Future of Work (AOFOW) - Podcast