The quality or state of being duncish; foolishness or lack of intelligence.
From 'duncish' with the noun-forming suffix '-ness,' which creates abstract nouns from adjectives (as in 'kindness,' 'darkness,' 'foolishness'). The '-ness' suffix comes from Old English.
The suffix '-ness' turns any adjective into something you can measure or discuss as a concept—'duncishness' is what you'd use in a formal or humorous way to talk about someone's persistent foolishness as if it were a measurable trait.
Complete word intelligence in one call. Free tier — 50 lookups/day.