The quality or state of being doleful; deep sadness, sorrow, or melancholy.
From doleful (adjective: full of sorrow) + -ness (suffix forming abstract nouns). This became a standard noun form in English to describe the abstract quality of grief or mourning.
The suffix '-ness' is one of the most productive tools in English for turning feelings into measurable qualities—'dolefulness' lets us talk about sadness as if it's an ingredient we can weigh and study scientifically.
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