What term refers to fashionable intellectual & social gatherings during the Rococo period that were hosted by aristocratic women?
I think that the word you are looking for is "salon." Salons were "fashionable intellectual and social gatherings" which were, indeed, hosted by aristocratic women during that period.
According to Wikipedia, Salons were:
Gatherings of people under the roof of an inspiring host, held partly to amuse one another and partly to refine taste and increase their knowledge of the participants through conversation. These gatherings often consciously followed Horace's definition of the aims of poetry, "either to please or to educate" ("aut delectare aut prodesse est"). Salons, commonly associated with French literary and philosophical movements of the 17th century and 18th centuries, were carried on until quite recently, in urban settings, among like-minded people.