A deadly illness is referred to as?

A deadly illness is referred to as a terminal illness because this term specifically describes a condition that is expected to lead to death, either due to the nature of the illness itself or through its complications. Terminal illnesses often have no effective cure and generally indicate a substantial limit on the expected lifespan of the affected individual.

While congestive heart failure, dementia, and heart attacks can all have severe consequences and may indeed be life-threatening, they do not necessarily align with the definition of "terminal illness" in every case. For instance, some individuals with congestive heart failure may manage their condition with treatment, and dementia varies significantly in progression and impact. A heart attack can be fatal, but timely medical intervention can often lead to recovery, meaning it does not strictly qualify as terminal. Therefore, the most accurate and encompassing term for a deadly illness, particularly one from which recovery is not anticipated, is terminal illness.