n. 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.
the GNU version of the Collaborative International Dictionary of English
n. The operation of opening the fetal head, in order to effect delivery.
The Century Dictionary and Cyclopedia
n. In obstetrics, an operation in which the fetal head is opened when it presents an obstacle to delivery.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a surgical opening through the skull
Word Usage
"Such an injury requires emergency surgery known as a craniotomy - where a hole is put in the skull, to let the blood out and so release cerebral pressure."