bluestocking: [18] The term bluestocking ‘female intellectual’ derives from the gatherings held at the houses of fashionable mid-18th- century hostesses to discuss literary and related topics. It became the custom at these not to put on full formal dress, which for gentlemen included black silk stockings. One habitué in particular, Mr Benjamin Stillingfleet, used to wear greyish worsted stockings, conventionally called ‘blue’.
This lack of decorum was looked on with scorn in some quarters, and Admiral Boscawan dubbed the participants the ‘Blue Stocking Society’. Women who attended their highbrow meetings thus became known as ‘Blue Stocking Ladies’ (even though it was a man who had worn the stockings), and towards the end of the century this was abbreviated to simply bluestockings. [bluestocking etymology, bluestocking origin, 英语词源]