"meurtrier de masse" meaning in French

{
  "forms": [
    {
      "form": "meurtriers de masse",
      "tags": [
        "plural"
      ]
    },
    {
      "form": "meurtrière de masse",
      "tags": [
        "feminine"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "m",
        "f": "+"
      },
      "expansion": "meurtrier de masse m (plural meurtriers de masse, feminine meurtrière de masse)",
      "name": "fr-noun"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "French 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": "fr",
          "name": "Murder",
          "orig": "fr:Murder",
          "parents": [
            "Crime",
            "Death",
            "Violence",
            "Criminal law",
            "Society",
            "Body",
            "Life",
            "Human behaviour",
            "Law",
            "All topics",
            "Nature",
            "Human",
            "Justice",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "mass murderer"
      ],
      "id": "en-meurtrier_de_masse-fr-noun-gehH-2ke",
      "links": [
        [
          "mass murderer",
          "mass murderer"
        ]
      ],
      "synonyms": [
        {
          "word": "tueur de masse"
        }
      ],
      "tags": [
        "masculine"
      ]
    }
  ],
  "word": "meurtrier de masse"
}

{
  "forms": [
    {
      "form": "meurtriers de masse",
      "tags": [
        "plural"
      ]
    },
    {
      "form": "meurtrière de masse",
      "tags": [
        "feminine"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "m",
        "f": "+"
      },
      "expansion": "meurtrier de masse m (plural meurtriers de masse, feminine meurtrière de masse)",
      "name": "fr-noun"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "French countable nouns",
        "French entries with incorrect language header",
        "French lemmas",
        "French masculine nouns",
        "French multiword terms",
        "French nouns",
        "Pages with 1 entry",
        "Pages with entries",
        "fr:Murder"
      ],
      "glosses": [
        "mass murderer"
      ],
      "links": [
        [
          "mass murderer",
          "mass murderer"
        ]
      ],
      "synonyms": [
        {
          "word": "tueur de masse"
        }
      ],
      "tags": [
        "masculine"
      ]
    }
  ],
  "word": "meurtrier de masse"
}