"Nantiacum" meaning in Latin

{
  "categories": [
    {
      "kind": "other",
      "name": "Localités de Gaule en latin",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Mots en latin issus d’un mot en gaulois",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Noms propres en latin",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Latin",
      "orig": "latin",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Étymologies en latin incluant une reconstruction",
      "parents": [],
      "source": "w"
    }
  ],
  "etymology_texts": [
    "Apparenté à Nantuates ; toponyme gaulois ^([1]), de *nanto, « vallée » → voir Nantiat, Nanthiat, Nandy, Nançay, Nangy, Nance, Nances et Nançois."
  ],
  "forms": [
    {
      "form": "Nantiacī",
      "tags": [
        "singular",
        "genitive"
      ]
    },
    {
      "form": "Nantiacō",
      "tags": [
        "singular",
        "dative"
      ]
    },
    {
      "form": "Nantiacō",
      "tags": [
        "singular",
        "ablative"
      ]
    }
  ],
  "lang": "Latin",
  "lang_code": "la",
  "pos": "name",
  "pos_title": "Nom propre",
  "related": [
    {
      "word": "Nancium"
    },
    {
      "word": "Nanceium"
    }
  ],
  "senses": [
    {
      "glosses": [
        "Ville de la Gaule belgique, actuelle Nancy."
      ],
      "id": "fr-Nantiacum-la-name-3BQORse7"
    }
  ],
  "tags": [
    "neuter"
  ],
  "word": "Nantiacum"
}

{
  "categories": [
    "Localités de Gaule en latin",
    "Mots en latin issus d’un mot en gaulois",
    "Noms propres en latin",
    "latin",
    "Étymologies en latin incluant une reconstruction"
  ],
  "etymology_texts": [
    "Apparenté à Nantuates ; toponyme gaulois ^([1]), de *nanto, « vallée » → voir Nantiat, Nanthiat, Nandy, Nançay, Nangy, Nance, Nances et Nançois."
  ],
  "forms": [
    {
      "form": "Nantiacī",
      "tags": [
        "singular",
        "genitive"
      ]
    },
    {
      "form": "Nantiacō",
      "tags": [
        "singular",
        "dative"
      ]
    },
    {
      "form": "Nantiacō",
      "tags": [
        "singular",
        "ablative"
      ]
    }
  ],
  "lang": "Latin",
  "lang_code": "la",
  "pos": "name",
  "pos_title": "Nom propre",
  "related": [
    {
      "word": "Nancium"
    },
    {
      "word": "Nanceium"
    }
  ],
  "senses": [
    {
      "glosses": [
        "Ville de la Gaule belgique, actuelle Nancy."
      ]
    }
  ],
  "tags": [
    "neuter"
  ],
  "word": "Nantiacum"
}