Synonyms for Evening gown:

n.

•clothing (noun)
doublet, bonnet, pull over, raincoat, crinoline, blouse, turtle-neck, attire, burnoose, shorts, blazer, cloak, fur, v neck, gown, skirt, cape, sarong, jersey, petticoat, wrapper, dress, apparel, coat, shirt, smock, brassiere, homburg, sari, caftan, windbreaker, clothing, tunic, pyjamas, corset, parka, dressing gown, smoking jacket, outfit, trench coat, jacket, afghan, pants, clothes, duds, pillbox, pinafore, ensemble, kimono, bathrobe, hat, shawl, footgear, panties, bowler, greatcoat, scarf, garment, raiment, poncho, nightgown, sweater, vesture, pea coat, trousers, camisole, array, shoes, chemise, stetson, stockings, fez, overcoat, t-shirt, costume, tuxedo, vestment, ulster, fedora, sweat suit, pajamas, boot, beret, slacks, sports coat, topcoat, trimming, chapeau, sweat shirt, habit, halter, wrap, mackintosh, housecoat, slicker, kilt, robe, garb, frock, jumper, suit, dinner jacket, headdress, blue jeans.
•evening gown (noun)
dinner gown, tea gown, dinner dress.

Other synonyms:

•Other relevant words:
dinner gown, dinner dress.