"◌̈" meaning in French

{
  "lang": "French",
  "lang_code": "fr",
  "pos": "character",
  "senses": [
    {
      "categories": [
        {
          "kind": "topical",
          "name": "French 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": "French entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "French terms in nonstandard scripts",
          "parents": [
            "Terms in nonstandard scripts",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "tréma; when placed above a letter, indicates that the vowel letter should be pronounced separately from a vowel letter next to it."
      ],
      "id": "en-◌̈-fr-character-T6wEwL~8",
      "links": [
        [
          "tréma",
          "tréma#English"
        ]
      ],
      "tags": [
        "diacritic"
      ]
    }
  ],
  "word": "◌̈"
}

{
  "lang": "French",
  "lang_code": "fr",
  "pos": "character",
  "senses": [
    {
      "categories": [
        "French diacritical marks",
        "French entries with incorrect language header",
        "French lemmas",
        "French terms in nonstandard scripts"
      ],
      "glosses": [
        "tréma; when placed above a letter, indicates that the vowel letter should be pronounced separately from a vowel letter next to it."
      ],
      "links": [
        [
          "tréma",
          "tréma#English"
        ]
      ],
      "tags": [
        "diacritic"
      ]
    }
  ],
  "word": "◌̈"
}