Septic shock definitions are being revisited. We assess the feasibility, reliability, and validity characteristics of the current definitions and criteria of septic shock. Septic shock is conceptualised as cardiovascular dysfunction, tissue perfusion and cellular abnormalities caused by infection. Currently, for feasibility, septic shock is identified at the bedside by using either hypotension or a proxy for tissue perfusion/cellular abnormalities (e.g., hyperlactatemia). We propose that concurrent presence of cardiovascular dysfunction and perfusion/cellular abnormalities could improve validity of septic shock diagnosis, as we are more likely to identify a patient population with all elements of the illness concept. This epidemiological refinement should not affect clinical care and may aid study design to identify illness-specific biomarkers and interventions.