"H0" meaning in Anglais

{
  "categories": [
    {
      "kind": "other",
      "name": "Abréviations en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Dates manquantes en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Lemmes en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Noms communs en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Anglais",
      "orig": "anglais",
      "parents": [],
      "source": "w"
    }
  ],
  "etymology_texts": [
    "(Date à préciser) Abréviation de half 0 car le rapport 1:87 est la moitié du 0 dont la rapport est 1:43,5."
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "noun",
  "pos_title": "Nom commun",
  "related": [
    {
      "word": "HO"
    }
  ],
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Lexique en anglais du modélisme",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Wiktionnaire:Exemples manquants en anglais",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Échelle correspondant au rapport 1:87."
      ],
      "id": "fr-H0-en-noun-Z7g3BADj",
      "raw_tags": [
        "Modélisme"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "\\hɛɪ̯t͡ʃ.ow\\"
    }
  ],
  "tags": [
    "invariable"
  ],
  "word": "H0"
}

{
  "categories": [
    "Abréviations en anglais",
    "Dates manquantes en anglais",
    "Lemmes en anglais",
    "Noms communs en anglais",
    "anglais"
  ],
  "etymology_texts": [
    "(Date à préciser) Abréviation de half 0 car le rapport 1:87 est la moitié du 0 dont la rapport est 1:43,5."
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "noun",
  "pos_title": "Nom commun",
  "related": [
    {
      "word": "HO"
    }
  ],
  "senses": [
    {
      "categories": [
        "Lexique en anglais du modélisme",
        "Wiktionnaire:Exemples manquants en anglais"
      ],
      "glosses": [
        "Échelle correspondant au rapport 1:87."
      ],
      "raw_tags": [
        "Modélisme"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "\\hɛɪ̯t͡ʃ.ow\\"
    }
  ],
  "tags": [
    "invariable"
  ],
  "word": "H0"
}