diaper corset
Diaper corsets are a type of diapersuit (a type of diaper that covers more of the body) that only covers the torso area of the body.
They are designed to look sort of like a corset, hence the name.
The adsorbent part of the diaper runs up the length of the back and front of the diaper, this is important as this is what makes an actual diaper corset.