Definition of "costumed"

For a livelier scene, head here on Friday or Saturday night, when mass beer-sculling (chugging) and yodeling are accompanied by a brass band and costumed waitresses ferrying foaming beer steins about the atmospheric, cellarlike space.

2006, Marc Llewellyn, Lee Mylne, Frommer′s Australia from $60 a Day, 14th edition, page 133