fatal

Fatal is an adjective used to describe events, injuries, diseases, or conditions that cause death or are likely to cause death. It is commonly applied to situations such as a fatal accident, a fatal illness, or a fatal wound, where death is the outcome. The term can also describe consequences that are calamitous or irreversibly ruinous, for example a fatal mistake or a fatal flaw that undermines a plan or system. In safety and medical contexts, fatal is used to distinguish outcomes that include fatalities from non-fatal outcomes.

From Latin fatalis, meaning "fated, destined to happen," from fatum "fate." In English usage, fatal conveys finality and severity; it can indicate inevitability, but it does not always imply certainty. Lethal and deadly are related terms that focus more on the capacity to cause death, whereas fatal emphasizes the death that results.

Related terms include deadly, lethal, mortal, and fatalism. Fatalism refers to the philosophical belief that events are predetermined and inevitable, regardless of human action.