…It was the fashion to wear the outer robe open, so the front part of the waistcoat began to be elaborately embroidered and embellished. It was used to cover and hide the fastenings, and became the “stomacher” or “placard”.
(Portrait: Woman in early 16th century Italian ornate “placard” under open gown. Note how the huge manly figure was emphasized in portraiture of noble women at the time)