"spilla sifjum" meaning in Old Norse

{
  "head_templates": [
    {
      "args": {
        "1": "non",
        "2": "verb"
      },
      "expansion": "spilla sifjum",
      "name": "head"
    }
  ],
  "lang": "Old Norse",
  "lang_code": "non",
  "pos": "verb",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Old Norse 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"
        }
      ],
      "examples": [
        {
          "english": "Brothers shall fight and fell each other; sisters’ sons will defile the kinship;",
          "text": "10th century, Vǫluspá\nBrǿðr munu bęrjask · ok at bǫnum verðask,\nmunu systrungar · sifjum spilla;",
          "type": "quotation"
        }
      ],
      "glosses": [
        "to \"defile kinship\"; to commit incest"
      ],
      "id": "en-spilla_sifjum-non-verb-d6d~uOu8",
      "links": [
        [
          "commit",
          "commit"
        ],
        [
          "incest",
          "incest"
        ]
      ],
      "raw_glosses": [
        "(poetic) to \"defile kinship\"; to commit incest"
      ],
      "related": [
        {
          "english": "kinship-defilement; incest",
          "word": "sifjaspell"
        }
      ],
      "tags": [
        "poetic"
      ]
    }
  ],
  "word": "spilla sifjum"
}

{
  "head_templates": [
    {
      "args": {
        "1": "non",
        "2": "verb"
      },
      "expansion": "spilla sifjum",
      "name": "head"
    }
  ],
  "lang": "Old Norse",
  "lang_code": "non",
  "pos": "verb",
  "related": [
    {
      "english": "kinship-defilement; incest",
      "word": "sifjaspell"
    }
  ],
  "senses": [
    {
      "categories": [
        "Old Norse entries with incorrect language header",
        "Old Norse lemmas",
        "Old Norse multiword terms",
        "Old Norse poetic terms",
        "Old Norse terms with quotations",
        "Old Norse verbs",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "examples": [
        {
          "english": "Brothers shall fight and fell each other; sisters’ sons will defile the kinship;",
          "text": "10th century, Vǫluspá\nBrǿðr munu bęrjask · ok at bǫnum verðask,\nmunu systrungar · sifjum spilla;",
          "type": "quotation"
        }
      ],
      "glosses": [
        "to \"defile kinship\"; to commit incest"
      ],
      "links": [
        [
          "commit",
          "commit"
        ],
        [
          "incest",
          "incest"
        ]
      ],
      "raw_glosses": [
        "(poetic) to \"defile kinship\"; to commit incest"
      ],
      "tags": [
        "poetic"
      ]
    }
  ],
  "word": "spilla sifjum"
}