"isna" meaning in Old Irish

{
  "head_templates": [
    {
      "args": {
        "1": "sga",
        "2": "article form"
      },
      "expansion": "isna",
      "name": "head"
    }
  ],
  "lang": "Old Irish",
  "lang_code": "sga",
  "pos": "article",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Old Irish entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Old Irish univerbations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 3 entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Univerbation of hi (“in”) + inna (“the”, accusative plural)"
      ],
      "id": "en-isna-sga-article-PoiEcPxt",
      "links": [
        [
          "hi",
          "hi#Old_Irish"
        ],
        [
          "inna",
          "inna#Old_Irish"
        ]
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[ˈisn͈a]"
    }
  ],
  "word": "isna"
}

{
  "head_templates": [
    {
      "args": {
        "1": "sga",
        "2": "article form"
      },
      "expansion": "isna",
      "name": "head"
    }
  ],
  "lang": "Old Irish",
  "lang_code": "sga",
  "pos": "article",
  "senses": [
    {
      "categories": [
        "Old Irish article forms",
        "Old Irish entries with incorrect language header",
        "Old Irish non-lemma forms",
        "Old Irish univerbations",
        "Pages with 3 entries"
      ],
      "glosses": [
        "Univerbation of hi (“in”) + inna (“the”, accusative plural)"
      ],
      "links": [
        [
          "hi",
          "hi#Old_Irish"
        ],
        [
          "inna",
          "inna#Old_Irish"
        ]
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[ˈisn͈a]"
    }
  ],
  "word": "isna"
}