"X̄" meaning in Latin

{
  "head_templates": [
    {
      "args": {
        "1": "X̄<0>",
        "g": "m"
      },
      "expansion": "X̄ m sg (indeclinable)",
      "name": "la-prop"
    }
  ],
  "lang": "Latin",
  "lang_code": "la",
  "pos": "name",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Latin entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Medieval Latin",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 2 entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Scribal abbreviation of Christus."
      ],
      "id": "en-X̄-la-name-k6VVdPRV",
      "links": [
        [
          "Christus",
          "Christus#Latin"
        ]
      ],
      "raw_glosses": [
        "(Medieval Latin) Scribal abbreviation of Christus."
      ],
      "tags": [
        "Medieval-Latin",
        "indeclinable",
        "masculine",
        "singular"
      ]
    }
  ],
  "word": "X̄"
}

{
  "head_templates": [
    {
      "args": {
        "1": "X̄<0>",
        "g": "m"
      },
      "expansion": "X̄ m sg (indeclinable)",
      "name": "la-prop"
    }
  ],
  "lang": "Latin",
  "lang_code": "la",
  "pos": "name",
  "senses": [
    {
      "categories": [
        "Latin entries with incorrect language header",
        "Latin indeclinable nouns",
        "Latin lemmas",
        "Latin masculine indeclinable nouns",
        "Latin masculine nouns",
        "Latin proper nouns",
        "Latin scribal abbreviations",
        "Latin terms spelled with ◌̄",
        "Medieval Latin",
        "Pages with 2 entries"
      ],
      "glosses": [
        "Scribal abbreviation of Christus."
      ],
      "links": [
        [
          "Christus",
          "Christus#Latin"
        ]
      ],
      "raw_glosses": [
        "(Medieval Latin) Scribal abbreviation of Christus."
      ],
      "tags": [
        "Medieval-Latin",
        "indeclinable",
        "masculine",
        "singular"
      ]
    }
  ],
  "word": "X̄"
}