A Cache-cœur ( French for "hide the heart") is a

top A spinning top, or simply a top, is a toy with a squat body and a sharp point at the bottom, designed to be spun on its vertical axis, balancing on the tip due to the gyroscopic effect. Once set in motion, a top will usually wobble for a few ...

for women, composed of two finished triangular parts, each having a strap. It is closed by overlapping the two segments and tying the straps behind the back or along the side, depending on the length. The triangular shape of the sides makes the garment a type of V-neck.

References

Tops (clothing) {{clothing-stub