A widow endowed, or having a jointure; a widow who either enjoys a dower from her deceased husband, or has property of her own brought by her to her husband on marriage, and settled on her after his decease.
the widow of a nobleman. For example: the Duke of Cheese, being old and moldy, dies. His wife becomes the Dowager Duchess of Cheese. Their eldest son inherits the title, and his wife becomes the new Duchess of Cheese, just as he becomes the new Duke. So, the new Duke's wife is the Duchess; his mother is the Dowager Duchess.