Wiktionary
n. 1 A woman who is socially prominent, respected, and experienced, especially one who is haughty and advanced in age. 2 A woman who is accomplished, influential, and a senior figure in a particular field. 3 (context figuratively by extension English) A well-known, very highly regarded institution, structure, or large conveyance, such as a hotel or ship.
WordNet
n. a woman of great prestige or ability
Usage examples of "grande dame".
You accepted your post here with us, said the grande dame, because of your fear of death, and I because of honor-because it was not in me to reject the honor and esteem.
On the surface the interview was precisely what I would have expected: the grande dame dismissing the now inconvenient hireling, but expecting him to accomplish the impossible before she threw him out, and the hireling resenting the whole business.
I saw the ancestor stiffen, and I knew she was about to go into her grande dame act.
Gerard cooked in the apartment and she played the grande dame again and Rosetti dutifully played up to her.