Ageism is a widely used term that is not (yet) well understood. We propose a redefinition of ageism and to separate it from ableism. We believe this to be important as remedies may depend on whether someone is experiencing ageism or ableism. While focusing the discussion on older workers as a sub-group of older people who (can) experience ageism, we assess the usefulness of critical (feminist) disability studies for ageism research. We hope that redefining ageism and analytically separating it from ableism (without suggesting that both concepts should be studied independently from one another) will provide guidance for researchers who study ageism and will allow for more specific policy guidance on how to solve difficulties experienced by older workers.