craniotomy(n = noun.act) - a surgical opening through the skull;
is a kind of operation, surgery, surgical operation, surgical procedure, surgical process
The operation of opening the fetal head, in order to effect delivery. [1913 Webster]
craniotomy, n. (pl. -ies)
1 surgical removal of a portion of the skull.
2 surgical perforation of the skull of a dead foetus to ease delivery.