"a-a" meaning in English

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      "expansion": "a-a (uncountable)",
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "aa"
        }
      ],
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          "_dis": "10 6 11 26 10 7 4 27",
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      ],
      "examples": [
        {
          "ref": "1883, Clarence E. Dutton, Fourth Annual report of the United States Geological Survey",
          "text": "The second form of the lavas is called by the natives a-a, and its contrast with pahoehoe is about the greatest imaginable. It consists mainly of clinkers sometimes detached, sometimes partially agglutinated together with a bristling array of sharp, jagged, angular fragments."
        }
      ],
      "glosses": [
        "Alternative form of aa."
      ],
      "id": "en-a-a-en-noun-QyN3gC9o",
      "links": [
        [
          "aa",
          "aa#English"
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        "alt-of",
        "alternative",
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  "word": "a-a"
}

{
  "etymology_number": 2,
  "head_templates": [
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      "args": {
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      "expansion": "a-a (not comparable)",
      "name": "en-adj"
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  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "senses": [
    {
      "alt_of": [
        {
          "word": "air-to-air"
        }
      ],
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      ],
      "glosses": [
        "Abbreviation of air-to-air."
      ],
      "id": "en-a-a-en-adj-HRlu4php",
      "links": [
        [
          "air-to-air",
          "air-to-air#English"
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      "tags": [
        "abbreviation",
        "alt-of",
        "not-comparable"
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    }
  ],
  "word": "a-a"
}

{
  "categories": [
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    "English lemmas",
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    "English nouns",
    "English uncomparable adjectives",
    "English uncountable nouns",
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  "etymology_number": 1,
  "head_templates": [
    {
      "args": {
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      "expansion": "a-a (uncountable)",
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "aa"
        }
      ],
      "examples": [
        {
          "ref": "1883, Clarence E. Dutton, Fourth Annual report of the United States Geological Survey",
          "text": "The second form of the lavas is called by the natives a-a, and its contrast with pahoehoe is about the greatest imaginable. It consists mainly of clinkers sometimes detached, sometimes partially agglutinated together with a bristling array of sharp, jagged, angular fragments."
        }
      ],
      "glosses": [
        "Alternative form of aa."
      ],
      "links": [
        [
          "aa",
          "aa#English"
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  "word": "a-a"
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  "categories": [
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  "etymology_number": 2,
  "head_templates": [
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      "expansion": "a-a (not comparable)",
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  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "senses": [
    {
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        {
          "word": "air-to-air"
        }
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      ],
      "glosses": [
        "Abbreviation of air-to-air."
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  ],
  "word": "a-a"
}