1. Resembling a sieve. (wiktionary.org)
2. Relating to, or in the region of, the ethmoid bone. (wiktionary.org)
Noun, pl. ethmoids
1. A square bone at the root of the nose, forming part of the cranium, and having many perforations through which the olfactory nerves pass to the nose. (Google Dictionary)
2. Ethmoid bone.
b. A bone in the skull that separates the nasal cavity from the brain. It is located at the roof of the nose, between the two orbits. The cubical bone is lightweight due to a spongy construction. The ethmoid bone is one of the bones that makes up the orbit of the eye. (wikipedia.org)
Word origin: From Ancient Greek ἠθμοειδής (ēthmoeidēs, “like a strainer or sieve”), from ἠθμός (ēthmos, “a strainer, colander, sieve”), from ἤθειν (ēthein, “to sift, strain”).