1. A short term for the spongy or sievelike ethmoid bone, a spongy bone that serves as the front floor of the skull and the roof of the nose.
2. Another short term for the ethmoid sinus, which is made up of numerous thin-walled air cells within the ethmoid bone.
3. Relating to, or being a light spongy bone located between the orbits, forming part of the walls and septum of the superior nasal cavity, and containing numerous perforations for the passage of the fibers of the olfactory nerves.