"grammatical alternation" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "de",
        "3": "grammatischer Wechsel"
      },
      "expansion": "Calque of German grammatischer Wechsel",
      "name": "calque"
    }
  ],
  "etymology_text": "Calque of German grammatischer Wechsel.",
  "forms": [
    {
      "form": "grammatical alternations",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "~"
      },
      "expansion": "grammatical alternation (countable and uncountable, plural grammatical alternations)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Linguistics",
          "orig": "en:Linguistics",
          "parents": [
            "Language",
            "Social sciences",
            "Communication",
            "Sciences",
            "Society",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Verner alternation"
      ],
      "id": "en-grammatical_alternation-en-noun-cWqjh8Oe",
      "links": [
        [
          "linguistics",
          "linguistics"
        ],
        [
          "Verner alternation",
          "Verner alternation"
        ]
      ],
      "raw_glosses": [
        "(linguistics) Verner alternation"
      ],
      "synonyms": [
        {
          "word": "grammatischer Wechsel"
        },
        {
          "word": "Verner alternation"
        }
      ],
      "tags": [
        "countable",
        "uncountable"
      ],
      "topics": [
        "human-sciences",
        "linguistics",
        "sciences"
      ]
    }
  ],
  "word": "grammatical alternation"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "de",
        "3": "grammatischer Wechsel"
      },
      "expansion": "Calque of German grammatischer Wechsel",
      "name": "calque"
    }
  ],
  "etymology_text": "Calque of German grammatischer Wechsel.",
  "forms": [
    {
      "form": "grammatical alternations",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "~"
      },
      "expansion": "grammatical alternation (countable and uncountable, plural grammatical alternations)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms calqued from German",
        "English terms derived from German",
        "English uncountable nouns",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Linguistics"
      ],
      "glosses": [
        "Verner alternation"
      ],
      "links": [
        [
          "linguistics",
          "linguistics"
        ],
        [
          "Verner alternation",
          "Verner alternation"
        ]
      ],
      "raw_glosses": [
        "(linguistics) Verner alternation"
      ],
      "tags": [
        "countable",
        "uncountable"
      ],
      "topics": [
        "human-sciences",
        "linguistics",
        "sciences"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "grammatischer Wechsel"
    },
    {
      "word": "Verner alternation"
    }
  ],
  "word": "grammatical alternation"
}