Foramen

[Sarah]

A small opening, perforation, or orifice; a fenestra. Foramenof Monro (Anat.), the opening from each lateral into the thirdventricle of the brain.-- Foramen of Winslow (Anat.), the opening connecting the sac of theomentum with the general cavity of the peritoneum.

[Oralee]

An opening, hole, or passage, especially in a bone.

[Couch Potatoe]

a natural passage in the body, especially into a bone