The quality or state of being deathful; deadliness or the presence of death.
From deathful + -ness suffix (forming nouns from adjectives). The -ness suffix comes from Old English and creates abstract nouns describing qualities.
By adding -ness to 'deathful,' we get a noun for the abstract quality of deadliness—it's like layering suffixes to climb higher into abstraction, from the concrete (death) to the descriptive (deathful) to the philosophical (deathfulness).
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