Ageism refers to a prejudicial view of older adults that characterizes them in negative ways.
Other definition:
Ageism refers to discrimination against people based on their age, specifically, discrimination against, and prejudicial stereotyping of, older people.
Other /More definition:
Ageism refers to n institutionalized tendency to discriminate on the basis of age; discrimination or prejudice based on a person's age. Ageism is prejudice against older people, similar to racism and sexism in its negative stereotypes. Ageism also refers to the untrue assumption that chronological age is the main determinant of human characteristics and that one age is better than another.