Dress Bergenia
The elasticated panel at the back means you can simply pull this dress over your head without the need for a fastener. The elasticity is achieved by sewing with elasticated thread. Alternatives to this technique would be sewing on flat elastic or small loops through which a string can be laced to adjust the panel to the correct width.
The neckline is quite large, so contouring is used to make it fit your body better. If you are working with your own set of measurements, I recommend adding the two values for shoulder contouring and neck contouring.