Dowager

A dowager is a widow who holds a title or property, or dower, derived from her deceased husband. As an adjective, "dowager" usually appears in association with monarchical and aristocratic titles.

In loose popular usage, dowager as a stand-alone noun may refer to any elderly widow, especially one who is wealthy or behaves with dignity.

Read more about Dowager:  Use in The United Kingdom, Monarchical Dowagers