• Webster's Revised Unabridged Dictionary
    • a Basioccipital (Anat) Of or pertaining to the bone in the base of the cranium, frequently forming a part of the occipital in the adult, but usually distinct in the young.
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Century Dictionary and Cyclopedia
    • basioccipital Pertaining to the base of the occiput, or to the basilar process of the occipital bone.
    • n basioccipital The centrum of the first (hindmost) cranial segment, forming the basis of the compound occipital bone, called in human anatomy the basilar process of the occipital, which anteriorly articulates or ankyloses with the basisphenoid, and posteriorly circumscribes in part the foramen magnum. Its normal union with two exoccipitals and a supraoccipital constitutes the thus compound occipital bone. See cuts under craniofacial, Crotalus, Esox, and Gallinæ.
    • n basioccipital In ichthyology, the lowest of the occipital bones. It is in the posterior part of the cranium, directly under the foramen magnum, and forms, usually with the assistance of the exoccipitals, the occipital condyle. The parasphenoid underlaps it anteriorly, while it articulates above with the exoccipitals and prootics.
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Webster's Revised Unabridged Dictionary
Basi-, + occipital,


In literature:

Since no sutures can be seen in this structure, it probably is the ventral, ossified portion of the basioccipital.
"A New Order of Fishlike Amphibia From the Pennsylvanian of Kansas" by Theodore H. Eaton
The median ridge on the basioccipital bone increases in prominence in older voles.
"A Population Study of the Prairie Vole (Microtus ochrogaster) in Northeastern Kansas" by Edwin P. Martin
In front of the basioccipital is the basisphenoid with an alisphenoid on each side.
"Encyclopaedia Britannica, 11th Edition, Volume 14, Slice 3" by Various