"Princess seams" is a term used in clothing design to describe seams that run vertically from the shoulder to the waist, creating a flattering, curved shape on the fabric. Full definition
As for the rest, here's one of my much visited posts on sewing princess seams. (sew2pro.com)
A feminine silhouette with princess seams for shape, chevron quilting, and an elegant faux - fur - trimmed hood that's removable to easily change your look. (garnethill.com)
Gauzy woven fabric, in a rust red, pink, and green floral print, shapes a ruffled neckline and princess seamed bodice. (lulus.com)