Moulded cup bra, ampliform model with pre-shaped cups and seamless versions: shapes that retain their curve even when not worn, and remain invisible under fine fabrics.
A moulded bra has shaped cups made from a single piece, which keep their shape even when laid flat. The boosted bra refers to a padded cup that is thicker at the bottom to add some curve. In both cases, the lack of seams on the cup is the key feature: it's this that makes the bra invisible under thin materials.
These three terms overlap and can be confusing. The moulded bra refers to the technique, a seamless cup. The boosted bra is a uniformly padded cup that adds a consistent volume without reshaping the bust. The push-up is an asymmetrically padded cup, thicker at the bottom and sides, designed to lift and bring the breasts closer together. In other words: all push-ups are moulded bras, but the reverse is not true.
This is its main purpose. Under a fine jersey, a silk blouse or a fitted dress, even the slightest seam on the cup can show. A smooth moulded bra in microfibre solves this problem, and so-called seamless models go even further by also eliminating the edges of the cups, which are laser-cut. For complete invisibility, choose a shade close to your skin tone rather than white: under light clothing, white stands out more than nude.