Which term describes discrimination based on a person's age?

The correct term that describes discrimination based on a person's age is ageism. Ageism encompasses stereotypes, prejudice, and discrimination directed against individuals solely based on their age, whether they are older adults or younger individuals. This concept highlights societal attitudes towards aging and age-related assumptions that can lead to negative treatment and marginalization of certain age groups.

In contrast, gerontology refers to the scientific study of aging and the challenges that older adults face, while aging describes the process of growing older without the implications of judgment that lie within ageism. Social justice pertains to the idea of fair treatment and equitable opportunities across all individuals, which can include fighting against ageism but does not directly define the discrimination itself. Therefore, ageism is the most precise term for discrimination based on age.