Small, roughly built houses or crude shelters, usually in poor condition.
Possibly from Japanese 'shaku' (a unit of measurement) or Nahuatl origin, though the exact source is debated; first appeared in American English in the 1800s referring to miners' rough dwellings.
The word 'shack' has such uncertain origins that linguists still debate it—it might come from Japanese, Aztec, or be completely made up, showing how some words just enter a language and nobody remembers why.
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