"刎頚之交" meaning in Japanese

{
  "forms": [
    {
      "form": "刎頸之交",
      "tags": [
        "alternative",
        "kanji",
        "kyūjitai"
      ]
    }
  ],
  "lang": "Japanese",
  "lang_code": "ja",
  "pos": "soft-redirect",
  "redirects": [
    "刎頸の交わり"
  ],
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Japanese terms with non-redundant non-automated sortkeys",
          "parents": [],
          "source": "w"
        }
      ],
      "id": "en-刎頚之交-ja-soft-redirect-47DEQpj8",
      "tags": [
        "no-gloss"
      ]
    }
  ],
  "word": "刎頚之交"
}

{
  "forms": [
    {
      "form": "刎頸之交",
      "tags": [
        "alternative",
        "kanji",
        "kyūjitai"
      ]
    }
  ],
  "lang": "Japanese",
  "lang_code": "ja",
  "pos": "soft-redirect",
  "redirects": [
    "刎頸の交わり"
  ],
  "senses": [
    {
      "categories": [
        "Japanese terms spelled with 之 read as の",
        "Japanese terms spelled with 交 read as まじ",
        "Japanese terms spelled with 刎 read as ふん",
        "Japanese terms spelled with 頚 read as けい",
        "Japanese terms with non-redundant non-automated sortkeys"
      ],
      "tags": [
        "no-gloss"
      ]
    }
  ],
  "word": "刎頚之交"
}