Originally denoted poorly clothed children but evolved to include neglected appearance in general. That actor really looks like a ragamuffin in his role as a street orphan.
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Negative Connotation
Carries a slightly negative or pitiful undertone when describing someone's appearance. He came back looking like a ragamuffin after the camping trip.
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Visual Imagery
Evokes a strong visual image of neglect or poverty, often used for emotive effect. The documentary showed ragamuffins scavenging through the city dump.