topectomySurg.|təˈpɛktəmɪ| [f. topo- + -ectomy.] An operation in which specific areas are removed from the frontal lobe of the cerebral cortex as a treatment for mental illness. 1948Newsweek 29 Mar. 47/3 In the new operation, called a topectomy, the brain fibers are not cut.1967[see gyrectomy].