"megawhaleback" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "mega",
        "3": "whaleback"
      },
      "expansion": "mega- + whaleback",
      "name": "prefix"
    }
  ],
  "etymology_text": "From mega- + whaleback.",
  "forms": [
    {
      "form": "megawhalebacks",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "megawhaleback (plural megawhalebacks)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English terms prefixed with mega-",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "langcode": "en",
          "name": "Geology",
          "orig": "en:Geology",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "A very large whaleback"
      ],
      "id": "en-megawhaleback-en-noun-pvxI4fPu",
      "links": [
        [
          "geology",
          "geology"
        ],
        [
          "whaleback",
          "whaleback"
        ]
      ],
      "raw_glosses": [
        "(geology) A very large whaleback"
      ],
      "topics": [
        "geography",
        "geology",
        "natural-sciences"
      ]
    }
  ],
  "word": "megawhaleback"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "mega",
        "3": "whaleback"
      },
      "expansion": "mega- + whaleback",
      "name": "prefix"
    }
  ],
  "etymology_text": "From mega- + whaleback.",
  "forms": [
    {
      "form": "megawhalebacks",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "megawhaleback (plural megawhalebacks)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English nouns",
        "English terms prefixed with mega-",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Geology"
      ],
      "glosses": [
        "A very large whaleback"
      ],
      "links": [
        [
          "geology",
          "geology"
        ],
        [
          "whaleback",
          "whaleback"
        ]
      ],
      "raw_glosses": [
        "(geology) A very large whaleback"
      ],
      "topics": [
        "geography",
        "geology",
        "natural-sciences"
      ]
    }
  ],
  "word": "megawhaleback"
}