An evening gown is a long flowing women's dress usually worn to a formal affair. It ranges from tea and ballerina to full-length. Evening gowns are often made of a luxury fabric such as chiffon, velvet, satin, or silk. Although the terms are used interchangeably, ball gowns and evening gowns differ in that a ball gown will always have a full, flared skirt and a strapless bodice; in contrast, an evening gown can be any silhouette—sheath, mermaid, A-line or trumpet shaped—and may have straps, halters or even sleeves. It corresponds to men's semi-formal wear for black tie events.     -Wikipedia