The Collaborative International Dictionary of English v.0.48:

Parethmoid \Par*eth"moid\, a. [Pref. para- + ethmoid.] (Anat.)
   Near or beside the ethmoid bone or cartilage; -- applied
   especially to a pair of bones in the nasal region of some
   fishes, and to the ethmoturbinals in some higher animals. --
   n. A parethmoid bone.
   [1913 Webster]