Straight
As its name says, the main characteristic of these dresses are the straight lines from the shoulders to the feet. This help to lengthen and slenderize your silhouette. Straight dreses, also known as "column dresses", can be fit, without marking the body, or more relaxed. Anyway, straight dresses are minimalistic garments which can have also a romantic touch. This is your silhouette if you are looking for a plain but modern design.
