An obsessive interest in or preoccupation with William Cowper and his works (a humorous or scholarly term).
From 'Cowper' (the poet) + '-itis' (a suffix meaning inflammation or disease, from Latin, humorously applied to excessive interest). This is a playful neologism used in literary circles.
Cowperitis is a great example of how English uses medical terminology to humorously describe passionate fandom—scholars and enthusiasts who are so devoted to studying a particular author that they get 'infected' with interest in them.
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