Plural form referring to multiple instances of dreadful things, or historically, cheap sensational novels featuring violent or lurid stories.
From dreadful (adjective) + -s (plural marker). In Victorian England, 'penny dreadfuls' were inexpensive serialized publications known for shocking content.
Victorian parents were so worried about 'penny dreadfuls' that they sound like the 1800s equivalent of video game panic—but historians now see them as early mass literature that made reading accessible to working-class kids.
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