womb + mate, on the model of roommate, etc.
wombmate (plural wombmates)
- A sibling with which an unborn child shares the womb.
- 1999, Judith Rich Harris, The Nurture Assumption: Why Children Turn Out the Way They Do
- The chance to meet one's wombmate, possibly for the first time since the umbilical cords were cut, is irresistible.