Deathfulness refers to the quality of being associated with death or bringing about death. There are several synonyms that can capture this meaning effectively, such as fatalness, lethality, and mortality. Fatalness refers to the ability to cause death or the state of being deadly. Lethality refers to the degree of deadliness of a substance or condition. Mortality refers to the condition or state of being subject to death. Other synonyms include deadliness, destructiveness, morbidity, and fatality. While all of these words capture the notion of deathfulness, they are nuanced in their connotations and contexts, which makes them useful for expressing different shades of meaning.