"forsa" meaning in Old Irish

{
  "etymology_number": 1,
  "etymology_templates": [
    {
      "args": {
        "1": "sga",
        "2": "for",
        "3": "-a",
        "id2": "relative",
        "pos2": "relative pronoun",
        "t1": "on"
      },
      "expansion": "for (“on”) + -a (relative pronoun)",
      "name": "af"
    }
  ],
  "etymology_text": "for (“on”) + -a (relative pronoun)",
  "forms": [
    {
      "form": "forsa·",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "sga",
        "2": "pronoun form",
        "cat2": "relative pronouns",
        "head": "forsa·"
      },
      "expansion": "forsa·",
      "name": "head"
    }
  ],
  "lang": "Old Irish",
  "lang_code": "sga",
  "pos": "pron",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Old Irish relative pronouns",
          "parents": [
            "Relative pronouns",
            "Pronouns",
            "Relative pro-forms",
            "Lemmas",
            "Pro-forms",
            "Terms by semantic function"
          ],
          "source": "w+disamb"
        },
        {
          "kind": "other",
          "name": "Old Irish terms suffixed with -a (relative)",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "42 58",
          "kind": "other",
          "name": "Old Irish univerbations",
          "parents": [],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "on whom, on which"
      ],
      "id": "en-forsa-sga-pron-7Hr-cwkh"
    }
  ],
  "sounds": [
    {
      "ipa": "[ˈɸor͈sa]"
    }
  ],
  "word": "forsa"
}

{
  "etymology_number": 2,
  "etymology_templates": [
    {
      "args": {
        "1": "sga",
        "2": "for",
        "3": "a",
        "pos2": "neuter accusative singular",
        "t1": "on",
        "t2": "the"
      },
      "expansion": "Univerbation of for (“on”) + a (“the”, neuter accusative singular)",
      "name": "univerbation"
    }
  ],
  "etymology_text": "Univerbation of for (“on”) + a (“the”, neuter accusative singular)",
  "head_templates": [
    {
      "args": {
        "1": "sga",
        "2": "article form",
        "3": "triggers eclipsis"
      },
      "expansion": "forsa (triggers eclipsis)",
      "name": "head"
    }
  ],
  "lang": "Old Irish",
  "lang_code": "sga",
  "pos": "article",
  "senses": [
    {
      "categories": [
        {
          "_dis": "100 0",
          "kind": "other",
          "name": "Old Irish entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "on the n sg"
      ],
      "id": "en-forsa-sga-article-sU8gTCiL",
      "tags": [
        "triggers-eclipsis"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[ˈɸor͈sa]"
    }
  ],
  "word": "forsa"
}

{
  "categories": [
    "Old Irish article forms",
    "Old Irish entries with incorrect language header",
    "Old Irish non-lemma forms",
    "Old Irish pronoun forms",
    "Old Irish relative pronouns",
    "Old Irish terms suffixed with -a (relative)",
    "Old Irish terms with IPA pronunciation",
    "Old Irish univerbations"
  ],
  "etymology_number": 1,
  "etymology_templates": [
    {
      "args": {
        "1": "sga",
        "2": "for",
        "3": "-a",
        "id2": "relative",
        "pos2": "relative pronoun",
        "t1": "on"
      },
      "expansion": "for (“on”) + -a (relative pronoun)",
      "name": "af"
    }
  ],
  "etymology_text": "for (“on”) + -a (relative pronoun)",
  "forms": [
    {
      "form": "forsa·",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "sga",
        "2": "pronoun form",
        "cat2": "relative pronouns",
        "head": "forsa·"
      },
      "expansion": "forsa·",
      "name": "head"
    }
  ],
  "lang": "Old Irish",
  "lang_code": "sga",
  "pos": "pron",
  "senses": [
    {
      "glosses": [
        "on whom, on which"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[ˈɸor͈sa]"
    }
  ],
  "word": "forsa"
}

{
  "categories": [
    "Old Irish article forms",
    "Old Irish entries with incorrect language header",
    "Old Irish non-lemma forms",
    "Old Irish terms with IPA pronunciation",
    "Old Irish univerbations"
  ],
  "etymology_number": 2,
  "etymology_templates": [
    {
      "args": {
        "1": "sga",
        "2": "for",
        "3": "a",
        "pos2": "neuter accusative singular",
        "t1": "on",
        "t2": "the"
      },
      "expansion": "Univerbation of for (“on”) + a (“the”, neuter accusative singular)",
      "name": "univerbation"
    }
  ],
  "etymology_text": "Univerbation of for (“on”) + a (“the”, neuter accusative singular)",
  "head_templates": [
    {
      "args": {
        "1": "sga",
        "2": "article form",
        "3": "triggers eclipsis"
      },
      "expansion": "forsa (triggers eclipsis)",
      "name": "head"
    }
  ],
  "lang": "Old Irish",
  "lang_code": "sga",
  "pos": "article",
  "senses": [
    {
      "glosses": [
        "on the n sg"
      ],
      "tags": [
        "triggers-eclipsis"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[ˈɸor͈sa]"
    }
  ],
  "word": "forsa"
}