"◌̄" meaning in Coptic

{
  "lang": "Coptic",
  "lang_code": "cop",
  "pos": "character",
  "senses": [
    {
      "categories": [
        {
          "kind": "topical",
          "name": "Coptic diacritical marks",
          "parents": [
            "Diacritical marks",
            "Letters, symbols, and punctuation",
            "Symbols",
            "Orthography",
            "Writing",
            "Human behaviour",
            "Language",
            "Human",
            "Communication",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Coptic entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Coptic terms in nonstandard scripts",
          "parents": [
            "Terms in nonstandard scripts",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 9 entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "The supralinear stroke, placed over a syllabic consonant."
      ],
      "id": "en-◌̄-cop-character-wYqTKcNf",
      "tags": [
        "diacritic"
      ]
    }
  ],
  "word": "◌̄"
}

{
  "lang": "Coptic",
  "lang_code": "cop",
  "pos": "character",
  "senses": [
    {
      "categories": [
        "Coptic diacritical marks",
        "Coptic entries with incorrect language header",
        "Coptic lemmas",
        "Coptic terms in nonstandard scripts",
        "Pages with 9 entries",
        "Pages with entries"
      ],
      "glosses": [
        "The supralinear stroke, placed over a syllabic consonant."
      ],
      "tags": [
        "diacritic"
      ]
    }
  ],
  "word": "◌̄"
}