CRANIOTOMY
craniotomy
(noun) a surgical opening through the skull
Source: WordNet® 3.1
Etymology
Noun
craniotomy (plural craniotomies)
(surgery) The surgical procedure for removing a part of the skull, called a bone flap, prior to a treatment. The bone flap is replaced at the end of the operation.
Source: Wiktionary
Cra`ni*ot"o*my (kr`n-t"-m), n. Etym: [Cranium + Gr. (Med.)
Definition: The operation of opening the fetal head, in order to effect
delivery.
Source: Webster’s Unabridged Dictionary 1913 Edition