"em quad" meaning in English

{
  "etymology_text": "Attested in 1841.\nFrom 1808 em quadrat, from 1683 m quadrat, from m + quadrat, a metal type, which is as wide as the point size of the font. The origin of the letter m is unclear; perhaps because the type body of the letter M was approximately square during the early days of typesetting, and to contrast it with the n quadrat, the letter n being approximately half as wide.",
  "forms": [
    {
      "form": "em quads",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "em quad (plural em quads)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English links with manual fragments",
          "parents": [
            "Links with manual fragments",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Typography",
          "orig": "en:Typography",
          "parents": [
            "Printing",
            "Writing",
            "Industries",
            "Human behaviour",
            "Language",
            "Business",
            "Human",
            "Communication",
            "Economics",
            "Society",
            "All topics",
            "Social sciences",
            "Fundamental",
            "Sciences"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Wikipedia with redundant first parameter",
          "orig": "wikipedia with redundant first parameter",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "A quad which has a fixed width of 1 em."
      ],
      "id": "en-em_quad-en-noun-qCAOvAuR",
      "links": [
        [
          "typography",
          "typography"
        ],
        [
          "quad",
          "quad#Etymology_4"
        ],
        [
          "em",
          "em"
        ]
      ],
      "raw_glosses": [
        "(typography) A quad which has a fixed width of 1 em."
      ],
      "related": [
        {
          "word": "em dash"
        },
        {
          "word": "em space"
        },
        {
          "word": "en quad"
        }
      ],
      "synonyms": [
        {
          "word": "em quadrat"
        },
        {
          "tags": [
            "obsolete"
          ],
          "word": "m quadrat"
        },
        {
          "word": "mutton quad"
        },
        {
          "word": "quad"
        }
      ],
      "topics": [
        "media",
        "publishing",
        "typography"
      ],
      "wikipedia": [
        "em quad"
      ]
    }
  ],
  "word": "em quad"
}

{
  "etymology_text": "Attested in 1841.\nFrom 1808 em quadrat, from 1683 m quadrat, from m + quadrat, a metal type, which is as wide as the point size of the font. The origin of the letter m is unclear; perhaps because the type body of the letter M was approximately square during the early days of typesetting, and to contrast it with the n quadrat, the letter n being approximately half as wide.",
  "forms": [
    {
      "form": "em quads",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "em quad (plural em quads)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "em dash"
    },
    {
      "word": "em space"
    },
    {
      "word": "en quad"
    }
  ],
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English links with manual fragments",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Typography",
        "wikipedia with redundant first parameter"
      ],
      "glosses": [
        "A quad which has a fixed width of 1 em."
      ],
      "links": [
        [
          "typography",
          "typography"
        ],
        [
          "quad",
          "quad#Etymology_4"
        ],
        [
          "em",
          "em"
        ]
      ],
      "raw_glosses": [
        "(typography) A quad which has a fixed width of 1 em."
      ],
      "topics": [
        "media",
        "publishing",
        "typography"
      ],
      "wikipedia": [
        "em quad"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "em quadrat"
    },
    {
      "tags": [
        "obsolete"
      ],
      "word": "m quadrat"
    },
    {
      "word": "mutton quad"
    },
    {
      "word": "quad"
    }
  ],
  "word": "em quad"
}