pterotic

from The Century Dictionary.

• In zoology and anatomy, noting an ossification of the periotic capsule or petrosal bone, distinct from the proötic, epiotic, and opisthotic, which occurs in some vertebrates between the proötic and the epiotic.
• noun A pterotic ossification. See first cut under teleost and cut under Esox.
• noun Specifically, in fishes, a posterolateral ossification of the cranium.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Anat.) Of or pertaining to, or designating, a bone between the proötic and epiotic in the dorsal and outer part of the periotic capsule of many fishes.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective anatomy Of or relating to a bone between the prootic and epiotic in the dorsal and outer part of the periotic capsule of many fishes.
• noun The pterotic bone.