Burnout has elicited growing interest among occupational health specialists in recent decades. Since 2019, the World Health Organization has characterized burnout as a syndrome resulting from chronic, unmanageable workplace stress. Accordingly, three symptoms define the entity: (i) feelings of energy depletion or exhaustion; (ii) increased mental distance from one’s job or feelings of negativism or cynicism towards one’s job; and (iii) a sense of ineffectiveness and lack of accomplishment. We call into question the definition of burnout embodied in the Maslach Burnout Inventory and incorporated into the ICD-11. We draw stakeholders’ attention to the fact that burnout’s symptoms and etiology were defined prior to any systematic research. We show that (i) exhaustion, cynicism and inefficacy do not form a cohesive syndrome; and (ii) no clear evidence exists that burnout is primarily caused by work-related stress. We discuss the implications of these findings for the status the ICD-11 grants to burnout.