1. (archaic) The space between a bed and the wall.
2. A morning assembly or reception held in the bedroom of a fashionable French lady, in the 17th and 18th centuries.
Etymology: French, diminutive of rue, street.
I tried to do some research on the context of that archaic definition - surely they don't mean that crevice that my pen rolls into whenever I try to write in bed. I found this in a book by Alexander Hay Japp: "...the Bed stood out squarely in the room, with the head to the wall, and both sides free....It was only after...space became an object, that it occurred to their owners to set them closely in a corner....Before the bed was pushed up closely in the corner, it was customary to have an alley between the Bed and the wall, an open space called the 'ruelle'."
For the second definition, a lady would recline on her bed and her female friends and guests would gather around on chairs.