By definition, a dowager is a widow or an elderly woman who holds stately position. Dowagers typically have gained status in the form of title or possessions from their deceased spouses.
From Charlotte Brontë's Jane Eyre:
But the three most distinguished — partly, perhaps, because the tallest figures of the band — were the Dowager Lady Ingram and her daughters, Blanche and Mary. They were all three of the loftiest stature of women.
Henry James writes in The American:
It was muffled in sociability and urbanity, as an old dowager in her laces and strings of pearls.
And in Lord Byron's poem Don Juan:
Remember, or (if you can not) imagine,
Ye, who have kept your chastity when young,
While some more desperate dowager has been waging
Love with you, and been in the dog-days stung