"a'a" meaning in English

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  "lang_code": "en",
  "pos": "noun",
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          "ref": "1999, A. Ganeri, Violent Volcanoes:",
          "text": "A'a is thick, sticky lava which forms jagged, chunky rock when it cools.",
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        {
          "ref": "2004, Richard Fortey, The Earth, Folio Society, published 2011, page 44:",
          "text": "I overheard a geologist say that a good pair of boots can be rasped to bits on a‘a in a couple of months.",
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        "Alternative form of aa."
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  "word": "a'a"
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  "lang_code": "en",
  "pos": "noun",
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          "word": "aa"
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  "word": "a'a"
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