The quality or state of being mysterious, puzzling, or difficult to understand; the characteristic of being enigmatical.
From enigmatical + -ness (noun suffix forming abstract nouns). A complex derivation showing how English stacks suffixes to build new words.
This word is literally how English creates abstract concepts from adjectives—it's like saying 'the mysterousness of mysterousness.' The more you stack suffixes, the more technical and formal it sounds!
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