Lobotomy (Greek: λοβός – lobos: "lobe (of brain)"; τομή – tomē: "cut/slice") is a neurosurgical procedure, a form of psychosurgery, also known as a leukotomy or leucotomy (from the Greek λευκός – leukos: "clear/white" and tome). It consists of cutting the connections to and from the prefrontal cortex, the anterior part of the frontal lobes of the brain. While the procedure, initially termed a leucotomy, has been controversial since its inception in 1935, it was a mainstream procedure for more than two decades, prescribed for psychiatric (and occasionally other) conditions—this despite general recognition of frequent and serious side-effects.

Half of the Nobel Prize for Physiology or Medicine of 1949 was awarded to António Egas Moniz for the "discovery of the therapeutic value of leucotomy in certain psychoses". The heyday of its usage was from the early 1940s until the mid-1950s when modern neuroleptic (antipsychotic) medications were introduced. By 1951, almost 20,000 lobotomies had been performed in the United States. The decline of the procedure was gradual rather than precipitous. In Ottawa's psychiatric hospitals, for instance, the 153 lobotomies performed in 1953 were reduced to 58 by 1961, after the arrival in Canada of the antipsychotic drug chlorpromazine in 1954. This method is an extreme method to calm insane people or people with swinging mood, not stable. It is used when all the other methods have failed. However, like any other psychosurgical procedures, it has some undesirable effects but can be control by medicine.