"fil rouge" meaning in French

{
  "etymology_templates": [
    {
      "args": {
        "1": "fr",
        "2": "de",
        "3": "roter Faden",
        "lit": "red thread",
        "nocap": "1"
      },
      "expansion": "calque of German roter Faden (literally “red thread”)",
      "name": "calque"
    }
  ],
  "etymology_text": "Literally “red thread.” Probably a calque of German roter Faden (literally “red thread”).",
  "forms": [
    {
      "form": "fils rouges",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "m"
      },
      "expansion": "fil rouge m (plural fils rouges)",
      "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": "Narratology",
          "orig": "fr:Narratology",
          "parents": [
            "Drama",
            "Literature",
            "Theater",
            "Culture",
            "Entertainment",
            "Writing",
            "Art",
            "Society",
            "Human behaviour",
            "Language",
            "All topics",
            "Human",
            "Communication",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "common thread, central theme, governing principle"
      ],
      "id": "en-fil_rouge-fr-noun-NQxwq8ZH",
      "links": [
        [
          "common thread",
          "common thread"
        ],
        [
          "central",
          "central"
        ],
        [
          "theme",
          "theme"
        ],
        [
          "governing",
          "governing"
        ],
        [
          "principle",
          "principle"
        ]
      ],
      "raw_glosses": [
        "(figuratively) common thread, central theme, governing principle"
      ],
      "related": [
        {
          "word": "fil d’Ariane"
        },
        {
          "word": "leitmotiv"
        }
      ],
      "synonyms": [
        {
          "word": "fil conducteur"
        }
      ],
      "tags": [
        "figuratively",
        "masculine"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/fil ʁuʒ/"
    }
  ],
  "word": "fil rouge"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "fr",
        "2": "de",
        "3": "roter Faden",
        "lit": "red thread",
        "nocap": "1"
      },
      "expansion": "calque of German roter Faden (literally “red thread”)",
      "name": "calque"
    }
  ],
  "etymology_text": "Literally “red thread.” Probably a calque of German roter Faden (literally “red thread”).",
  "forms": [
    {
      "form": "fils rouges",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "m"
      },
      "expansion": "fil rouge m (plural fils rouges)",
      "name": "fr-noun"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "noun",
  "related": [
    {
      "word": "fil d’Ariane"
    },
    {
      "word": "leitmotiv"
    }
  ],
  "senses": [
    {
      "categories": [
        "French countable nouns",
        "French entries with incorrect language header",
        "French lemmas",
        "French masculine nouns",
        "French multiword terms",
        "French nouns",
        "French nouns with red links in their headword lines",
        "French terms calqued from German",
        "French terms derived from German",
        "French terms with IPA pronunciation",
        "Pages with 1 entry",
        "Pages with entries",
        "fr:Narratology"
      ],
      "glosses": [
        "common thread, central theme, governing principle"
      ],
      "links": [
        [
          "common thread",
          "common thread"
        ],
        [
          "central",
          "central"
        ],
        [
          "theme",
          "theme"
        ],
        [
          "governing",
          "governing"
        ],
        [
          "principle",
          "principle"
        ]
      ],
      "raw_glosses": [
        "(figuratively) common thread, central theme, governing principle"
      ],
      "synonyms": [
        {
          "word": "fil conducteur"
        }
      ],
      "tags": [
        "figuratively",
        "masculine"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/fil ʁuʒ/"
    }
  ],
  "word": "fil rouge"
}