D defs.my
Entry 3 senses Webster, 1913

Costume

/(k?s"t?m` [or] k?s-t?m")/ · Cos·tume · IPA /ˈkɑsˌt(j)um/
01 n. Dress in general; esp., the distinctive style of dress of a people, class, or period.
  1. 1.
    Dress in general; esp., the distinctive style of dress of a people, class, or period.
  2. 2.
    Such an arrangement of accessories, as in a picture, statue, poem, or play, as is appropriate to the time, place, or other circumstances represented or described.
    “I began last night to read Walter Scott's Lay of the Last Minstrel . . . .I was extremely delighted with the poetical beauty of some parts . . . .The costume, too, is admirable.” — Sir J. Mackintosh.
  3. 3.
    A character dress, used at fancy balls or for dramatic purposes.