This Dancing With The Stars photo contains
demoiselle d'honneur and demoiselle d’honneur.
There might also be
robe de dîner, formel, robe de soirée, formelle, and robe.
See Carrie Ann Inaba's sexy new PETA ad she did on the set of her Animal Birth Control photo shoot with her adorable cat Shadow! She's such a sweetheart i l’amour her!! link