"13th grader" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "13th grade",
        "3": "er",
        "id2": "measurement"
      },
      "expansion": "13th grade + -er",
      "name": "suffix"
    }
  ],
  "etymology_text": "13th grade + -er",
  "forms": [
    {
      "form": "13th graders",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "13th grader (plural 13th graders)",
      "name": "en-noun"
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "thirteenth grader"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
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          "source": "w"
        },
        {
          "kind": "other",
          "name": "English terms suffixed with -er (measurement)",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Education",
          "orig": "en:Education",
          "parents": [
            "Society",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Alternative spelling of thirteenth grader"
      ],
      "id": "en-13th_grader-en-noun-4LP5N3zm",
      "links": [
        [
          "thirteenth grader",
          "thirteenth grader#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "13th grader"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "13th grade",
        "3": "er",
        "id2": "measurement"
      },
      "expansion": "13th grade + -er",
      "name": "suffix"
    }
  ],
  "etymology_text": "13th grade + -er",
  "forms": [
    {
      "form": "13th graders",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "13th grader (plural 13th graders)",
      "name": "en-noun"
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  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "thirteenth grader"
        }
      ],
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
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        "English multiword terms",
        "English nouns",
        "English terms spelled with numbers",
        "English terms suffixed with -er (measurement)",
        "en:Education"
      ],
      "glosses": [
        "Alternative spelling of thirteenth grader"
      ],
      "links": [
        [
          "thirteenth grader",
          "thirteenth grader#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
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    }
  ],
  "word": "13th grader"
}