"lady's loose robe," 1835, from French peignoir, from Middle French peignouoir "garment worn over the shoulders while combing the hair" (16c.), from peigner "to comb the hair," from Latin pectinare, from pecten (genitive pectinis) "a comb," related to pectere "to comb" (see fight (v.)). A gown put on while coming from the bath; misapplied in English to a woman's morning gown.
