Sentence:  Molly, therefore, having dressed herself out in this <WSD>sack</WSD>, with a new laced cap, and some other ornaments which Tom had given her, repairs to church with her fan in her hand the very next Sunday. 
Meaning of the word marked with <WSD> tags:  (also '''sacque''') A kind of loose-fitting gown or dress with sleeves which hangs from the shoulders, such as a gown with a Watteau back or sack-back, fashionable in the late 17th to 18th century; or, formerly, a loose-fitting hip-length jacket, cloak or cape.