trephination treph·i·na·tion (trěf'ə-nā'shən)
Removal of a circular piece of bone, especially of the skull, by a trephine. Also called trepanation.
trephine tre·phine (trĭ-fīn')
A cylindrical or crown saw for the removal of a disk of bone, especially from the skull, or removal of other firm tissue such as that of the cornea. v. tre·phined, tre·phin·ing, tre·phines
To operate on with a trephine.