The Collaborative International Dictionary
Ethmoid \Eth"moid\, Ethmoidal \Eth*moid"al\, a. [Gr. ? like a sieve; ? sieve + ? from: cf. F. ethmo["i]de, ethmo["i]dal.] (Anat.)
Like a sieve; cribriform.
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Pertaining to, or in the region of, the ethmoid bone.
Ethmoid bone (Anat.), a bone of complicated structure through which the olfactory nerves pass out of the cranium and over which they are largely distributed.
Wiktionary
a. ethmoid
WordNet
Usage examples of "ethmoidal".
The bone splattered, the ethmoidal sinus ruptured into the olfactory bulb, which meant Les Pruel could no longer smell anything, and the copper-pointed slug did a wing-ding puree of the cerebrum taking the top of his head off like an eggshell surrendering to compressed air.
On the lower surface of the frontal lobes there exists a strongly marked ethmoidal prominence.