1. The hole created by the ischium and pubis bones of the pelvis through which nerves and blood vessels pass. (wikipedia.org)
2. An opening that is the largest foramen in the human body, is situated between the ischium and pubis of the hip bone, and is closed by the obturator membrane except for the obturator canal. (merriam-webster.com)
3. A large opening in the hipbone between the pubis and the ischium. (Google Dictionary)
4. An opening situated between the public and ischial parts of the innominate bone and closed by the obturator membrane; the thyroid foramen.
Word origin: From Latin foramen “hole, opening, aperture, orifice,” from forare “to pierce.”