An empire waist, which is often shirred and has fabric billowing above and below it, refers to a fitting waistline that sits exactly below the bust on a dress or shirt. To know more, here is the article which you can read to learn more about it.
Empire Waistline
A dress with an empire waist has a fitted bodice that flares out beneath the bustline rather than at the natural waistline, and this form has the effects of extending and slimming the wearer. The bustline cinch lengthens the wearer’s frame because it creates a high, narrow waist and a long line of billowy fabric from breast to hem than if the dress were cinched at your natural waist. The necklines of this incredibly adaptable silhouette range from V-neck to turtleneck to halter top, and the sleeves can be long, short, or sleeveless.
Who can wear it?
Although the design is generally attractive, petite, plus-size, and pear-shaped women can draw attention away from their hips and waist and instead focus on their bust with these garments. The cut typically hides the stomach, draws attention to the breast, and creates the false impression that the waist is higher and slimmer than it truly is.