"2H" meaning in English

{
  "forms": [
    {
      "form": "2Hs",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "-",
        "2": "s"
      },
      "expansion": "2H (usually uncountable, plural 2Hs)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "British English",
          "parents": [],
          "source": "w"
        },
        {
          "_dis": "54 3 43",
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "66 6 28",
          "kind": "other",
          "name": "English words spelled without vowels",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "54 4 42",
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "60 4 37",
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "55 6 39",
          "kind": "other",
          "langcode": "en",
          "name": "Isotopes",
          "orig": "en:Isotopes",
          "parents": [],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "A grade of pencil with lead that makes lighter marks than a pencil grade H but darker marks than a pencil of grade 3H; a pencil with hard lead."
      ],
      "id": "en-2H-en-noun-1aDDtHWS",
      "links": [
        [
          "H",
          "H"
        ],
        [
          "3H",
          "3H"
        ]
      ],
      "raw_glosses": [
        "(British) A grade of pencil with lead that makes lighter marks than a pencil grade H but darker marks than a pencil of grade 3H; a pencil with hard lead."
      ],
      "tags": [
        "British",
        "uncountable",
        "usually"
      ]
    },
    {
      "glosses": [
        "A pencil of grade 2H."
      ],
      "id": "en-2H-en-noun-XEBfym0I",
      "tags": [
        "uncountable",
        "usually"
      ]
    },
    {
      "alt_of": [
        {
          "extra": "hydrogen-2",
          "word": "²H"
        }
      ],
      "categories": [
        {
          "_dis": "8 8 84",
          "kind": "other",
          "langcode": "en",
          "name": "Deuterium",
          "orig": "en:Deuterium",
          "parents": [],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "Alternative form of ²H (“hydrogen-2”)"
      ],
      "id": "en-2H-en-noun-mul:Q102296",
      "links": [
        [
          "²H",
          "²H#Translingual:_Q102296"
        ]
      ],
      "senseid": [
        "mul:Q102296"
      ],
      "tags": [
        "alt-of",
        "alternative",
        "uncountable",
        "usually"
      ],
      "wikidata": [
        "Q102296"
      ]
    }
  ],
  "word": "2H"
}

{
  "categories": [
    "English countable nouns",
    "English entries with incorrect language header",
    "English lemmas",
    "English nouns",
    "English terms spelled with numbers",
    "English uncountable nouns",
    "English words spelled without vowels",
    "Pages with 1 entry",
    "Pages with entries",
    "en:Deuterium",
    "en:Isotopes"
  ],
  "forms": [
    {
      "form": "2Hs",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "-",
        "2": "s"
      },
      "expansion": "2H (usually uncountable, plural 2Hs)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "British English"
      ],
      "glosses": [
        "A grade of pencil with lead that makes lighter marks than a pencil grade H but darker marks than a pencil of grade 3H; a pencil with hard lead."
      ],
      "links": [
        [
          "H",
          "H"
        ],
        [
          "3H",
          "3H"
        ]
      ],
      "raw_glosses": [
        "(British) A grade of pencil with lead that makes lighter marks than a pencil grade H but darker marks than a pencil of grade 3H; a pencil with hard lead."
      ],
      "tags": [
        "British",
        "uncountable",
        "usually"
      ]
    },
    {
      "glosses": [
        "A pencil of grade 2H."
      ],
      "tags": [
        "uncountable",
        "usually"
      ]
    },
    {
      "alt_of": [
        {
          "extra": "hydrogen-2",
          "word": "²H"
        }
      ],
      "glosses": [
        "Alternative form of ²H (“hydrogen-2”)"
      ],
      "links": [
        [
          "²H",
          "²H#Translingual:_Q102296"
        ]
      ],
      "senseid": [
        "mul:Q102296"
      ],
      "tags": [
        "alt-of",
        "alternative",
        "uncountable",
        "usually"
      ],
      "wikidata": [
        "Q102296"
      ]
    }
  ],
  "word": "2H"
}