"fil rouge" meaning in French

{
  "etymology_templates": [
    {
      "args": {
        "1": "fr",
        "2": "de",
        "3": "roter Faden",
        "nocap": "1"
      },
      "expansion": "calque of German roter Faden",
      "name": "calque"
    }
  ],
  "etymology_text": "Probably a calque of German roter Faden.",
  "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": "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",
        "nocap": "1"
      },
      "expansion": "calque of German roter Faden",
      "name": "calque"
    }
  ],
  "etymology_text": "Probably a calque of German roter Faden.",
  "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",
        "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"
}