1. Perform a lobotomy
   "In the mid-20th century, doctors would sometimes lobotomise patients with severe mental illnesses";
   - lobotomize
    
2. Reduce someone's level of mental functioning
   "The constant propaganda seemed to lobotomise the population, dulling their critical thinking skills";
   - lobotomize

Derived forms: lobotomised, lobotomises, lobotomising