"izeldir" meaning in Breton

{
  "antonyms": [
    {
      "word": "menez"
    },
    {
      "word": "uheldir"
    }
  ],
  "categories": [
    {
      "kind": "other",
      "name": "Lexique en breton de la géographie",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Noms communs en breton",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Breton",
      "orig": "breton",
      "parents": [],
      "source": "w"
    }
  ],
  "etymology_texts": [
    "→ voir izel et tir.",
    "Calque du mot gallois iseldir (sens identique).",
    "Mentionné dans le grand dictionnaire français-breton de François Vallée (1931).",
    "À comparer aussi avec le mot cornique yseldyr."
  ],
  "forms": [
    {
      "form": "iseldir",
      "raw_tags": [
        "orthographe interdialectale"
      ]
    }
  ],
  "lang": "Breton",
  "lang_code": "br",
  "pos": "noun",
  "pos_title": "Nom commun",
  "senses": [
    {
      "glosses": [
        "Basse terre."
      ],
      "id": "fr-izeldir-br-noun-KdT0Datl"
    },
    {
      "glosses": [
        "Plaine."
      ],
      "id": "fr-izeldir-br-noun-Ssxz5lUH"
    }
  ],
  "synonyms": [
    {
      "word": "dol"
    },
    {
      "word": "izelenn"
    },
    {
      "word": "traoñienn"
    }
  ],
  "tags": [
    "masculine",
    "plural"
  ],
  "word": "izeldir"
}

{
  "antonyms": [
    {
      "word": "menez"
    },
    {
      "word": "uheldir"
    }
  ],
  "categories": [
    "Lexique en breton de la géographie",
    "Noms communs en breton",
    "breton"
  ],
  "etymology_texts": [
    "→ voir izel et tir.",
    "Calque du mot gallois iseldir (sens identique).",
    "Mentionné dans le grand dictionnaire français-breton de François Vallée (1931).",
    "À comparer aussi avec le mot cornique yseldyr."
  ],
  "forms": [
    {
      "form": "iseldir",
      "raw_tags": [
        "orthographe interdialectale"
      ]
    }
  ],
  "lang": "Breton",
  "lang_code": "br",
  "pos": "noun",
  "pos_title": "Nom commun",
  "senses": [
    {
      "glosses": [
        "Basse terre."
      ]
    },
    {
      "glosses": [
        "Plaine."
      ]
    }
  ],
  "synonyms": [
    {
      "word": "dol"
    },
    {
      "word": "izelenn"
    },
    {
      "word": "traoñienn"
    }
  ],
  "tags": [
    "masculine",
    "plural"
  ],
  "word": "izeldir"
}