TREPHINATION By N., Pam M.S. - April 29, 2013 noun. a surgical process wherein a disk of bone is excised, generally from the cranium, with a circular tool having a saw-like edge. TREPHINATION: "Trephination of the skull is thought to be one of the earliest forms of surgery to have existed." Related Psychology Terms CRANIOGRAPH PAPILLEDEMA CRANIOTOMY CRANIOGRAPHY TOPECTOMY TEMPORAL HONE ANORTHOSCOPE OSTEOPETROSIS CRUTCH CRANIOSYNOSTOSIS SYNDROME Cite this page: N., Pam M.S., "TREPHINATION," in PsychologyDictionary.org, April 29, 2013, https://psychologydictionary.org/trephination/ (accessed February 23, 2020).