"Ei" meaning in Translingual

{
  "head_templates": [
    {
      "args": {
        "1": "mul",
        "2": "symbol"
      },
      "expansion": "Ei",
      "name": "head"
    }
  ],
  "lang": "Translingual",
  "lang_code": "mul",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Translingual entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Translingual entries with topic categories using raw markup",
          "parents": [
            "Entries with topic categories using raw markup",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "mul",
          "name": "Mathematics",
          "orig": "mul:Mathematics",
          "parents": [
            "Formal sciences",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "operatorname Ei(x)=∫-∞(eᵗ)/tdt"
        }
      ],
      "glosses": [
        "The exponential integral, a special function, defined as:",
        "The exponential integral, a special function, defined as"
      ],
      "id": "en-Ei-mul-noun-7HC~b9GM",
      "links": [
        [
          "special function",
          "special function"
        ]
      ],
      "raw_glosses": [
        "The exponential integral, a special function, defined as:"
      ],
      "wikipedia": [
        "Exponential integral"
      ]
    }
  ],
  "word": "Ei"
}

{
  "head_templates": [
    {
      "args": {
        "1": "mul",
        "2": "symbol"
      },
      "expansion": "Ei",
      "name": "head"
    }
  ],
  "lang": "Translingual",
  "lang_code": "mul",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "Translingual entries with incorrect language header",
        "Translingual entries with topic categories using raw markup",
        "Translingual lemmas",
        "Translingual symbols",
        "mul:Mathematics"
      ],
      "examples": [
        {
          "text": "operatorname Ei(x)=∫-∞(eᵗ)/tdt"
        }
      ],
      "glosses": [
        "The exponential integral, a special function, defined as:",
        "The exponential integral, a special function, defined as"
      ],
      "links": [
        [
          "special function",
          "special function"
        ]
      ],
      "raw_glosses": [
        "The exponential integral, a special function, defined as:"
      ],
      "wikipedia": [
        "Exponential integral"
      ]
    }
  ],
  "word": "Ei"
}