The state or quality of being feared; the condition of being dreaded or viewed with apprehension by others.
From 'feared' plus the noun-forming suffix '-ness,' which creates abstract nouns indicating states or qualities. This follows productive English word-formation patterns.
Nouns expressing abstract states like this one show how English's suffix system is incredibly generative—you can theoretically create '-ness' derivatives forever, but only a few stick around long enough to appear in actual dictionaries.
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