"年久しく" meaning in Japanese

{
  "forms": [
    {
      "form": "年久しく",
      "ruby": [
        [
          "年",
          "とし"
        ],
        [
          "久",
          "ひさ"
        ]
      ],
      "tags": [
        "canonical"
      ]
    },
    {
      "form": "toshihisashiku",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "adverb",
        "2": "としひさしく"
      },
      "expansion": "年(とし)久(ひさ)しく • (toshihisashiku)",
      "name": "ja-pos"
    }
  ],
  "lang": "Japanese",
  "lang_code": "ja",
  "pos": "adv",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Japanese entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Japanese links with redundant wikilinks",
          "parents": [
            "Links with redundant wikilinks",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Japanese terms with redundant sortkeys",
          "parents": [
            "Terms with redundant sortkeys",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "for many years"
      ],
      "id": "en-年久しく-ja-adv-cs54LJfz",
      "links": [
        [
          "year",
          "year"
        ]
      ]
    }
  ],
  "word": "年久しく"
}

{
  "forms": [
    {
      "form": "年久しく",
      "ruby": [
        [
          "年",
          "とし"
        ],
        [
          "久",
          "ひさ"
        ]
      ],
      "tags": [
        "canonical"
      ]
    },
    {
      "form": "toshihisashiku",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "adverb",
        "2": "としひさしく"
      },
      "expansion": "年(とし)久(ひさ)しく • (toshihisashiku)",
      "name": "ja-pos"
    }
  ],
  "lang": "Japanese",
  "lang_code": "ja",
  "pos": "adv",
  "senses": [
    {
      "categories": [
        "Japanese adverbs",
        "Japanese entries with incorrect language header",
        "Japanese lemmas",
        "Japanese links with redundant wikilinks",
        "Japanese terms spelled with fifth grade kanji",
        "Japanese terms spelled with first grade kanji",
        "Japanese terms with redundant sortkeys",
        "Japanese terms written with two Han script characters"
      ],
      "glosses": [
        "for many years"
      ],
      "links": [
        [
          "year",
          "year"
        ]
      ]
    }
  ],
  "word": "年久しく"
}

{
  "called_from": "parser/1336",
  "msg": "no corresponding start tag found for </span>",
  "path": [
    "年久しく"
  ],
  "section": "Japanese",
  "subsection": "adverb",
  "title": "年久しく",
  "trace": ""
}