The state or condition of being something that has been deplored or is worthy of disapproval.
From the adjective form deplored (past participle) + -ness (Germanic suffix for abstract nouns). A doubly suffixed formation that's extremely rare in actual usage.
Words like this exist in the theoretical grammar of English but almost never appear in real writing—they're the linguistic equivalent of legally possible but never-used chess moves, showing the difference between what a language can do and what it actually does.
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