The term bias cut, or cut on the bias, means that the fabric is cut on the cross grain rather than on the straight grain of the fabric. This enables the garment to stretch a little. Bias cut tape is used to stretch around curved edges being bound in sewing. Cutting fabric on the bias, or on the cross, also produces garments which can seductively cling to the body. There is no hiding of bulges when wearing a bias cut garment! Lingerie garments were often cut on the bias to add stretch without fullness in the days before stretch fabrics were available. Gowns cut on the bias were very popular in the 1930s. Think liquid satin and Jean Harlow. Designer Madeline Vionnet is famous for popularising gowns cut on the bias.
Embroidered Silk Nightgown cut on the bias