costumeyoudaoicibaDictYouDict[costume 词源字典]
costume: [18] Ultimately, costume and custom are the same word. Both come from Latin consuētūdō ‘custom’. But whereas custom was an early borrowing, from Old French, costume took a lengthier and more circuitous route via Italian costume ‘custom, fashion, dress’ and French costume. In the early 18th century the word referred to the custom or fashion of a particular period as it related to the representation of the clothes, furniture, etc of that period in art.

In the 19th century this passed into ‘mode of dress appropriate to a particular time or place’, and thence (completing a semantic development rather similar to that of habit) into simply ‘garments, outfit’.
=> custom[costume etymology, costume origin, 英语词源]
costume (n.)youdaoicibaDictYouDict
1715, "style of dress," an art term, from French costume (17c.), from Italian costume "fashion, habit," from Latin consuetudinem (nominative consuetudo) "custom, habit, usage." Essentially the same word as custom but arriving by a different etymology. From "customary clothes of the particular period in which the scene is laid," meaning broadened by 1818 to "any defined mode of dress." Costume jewelry is first attested 1933.
costume (v.)youdaoicibaDictYouDict
1823, from costume (n.). Related: Costumed; costuming.