ethmoid
- n one of the eight bones of the cranium; a small bone filled with air spaces that forms part of the eye sockets and the nasal cavity
- These bony caverns are called the frontal, maxillary or antrum, ethmoid and sphenoid sinuses.
- They are the occipital, the two parietals, the frontal, the two temporals, the sphenoid (wedge-formed) and the ethmoid (sieve-formed).