Plural of blotter; absorbent materials or pads used to soak up excess ink or liquid, or books recording police arrests.
From blot plus -er (agent suffix making 'one who blots') plus -s plural; blotters were essential office supplies before modern pens that didn't smudge.
Police blotters were public records of arrests, and newspapers would check them for stories—now everything's digital, but the term survives in phrases like 'checking the blotter' for overnight incidents.
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