A foolish or simple-minded person; someone easily confused or duped.
Compound of 'addle' (confused) + 'plot' (a person, probably from the Old English for 'plot of ground,' used here as a humorous euphemism for a foolish person).
This is one of the rarest and most obscure insults in English—'addleplot' appears occasionally in Middle English and early modern texts but faded away, possibly because other compound insults were more satisfying to say.
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